internet fundamentals module manual 2017

internet fundamentals module manual 2017
IIE Module Manual
INFU112
INTERNET FUNDAMENTALS
MODULE MANUAL 2017
This manual enjoys copyright under the Berne Convention. In terms of the Copyright
Act, no 98 of 1978, no part of this manual may be reproduced or transmitted in any
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from the proprietor.
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Higher Education Act, 1997 (reg. no. 2007/HE07/002).
Company registration number: 1987/004754/07.
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DID YOU KNOW?
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The full-service Student Portal provides you with access to your academic
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Table of Contents
Using this Manual ...................................................................................................... 7
Introduction ............................................................................................................... 8
Module Resources .................................................................................................... 9
Module Purpose ...................................................................................................... 12
Module Outcomes ................................................................................................... 12
Module Pacer .......................................................................................................... 13
Assessments ........................................................................................................... 15
Learning Unit 1: The Internet ................................................................................... 16
1 Introduction ...................................................................................................... 16
2 Recommended Additional Reading .................................................................. 16
3 Activities and Revision Exercises ..................................................................... 17
Learning Unit 2: Reference Models ......................................................................... 18
1 Introduction ...................................................................................................... 18
2 Recommended Additional Reading .................................................................. 18
3 Activities and Revision Exercises ..................................................................... 18
Learning Unit 3: Networks: Systems, Devices, Topologies and Technologies ......... 19
1 Introduction ...................................................................................................... 19
2 Recommended Additional Reading .................................................................. 19
3 Activities and Revision Exercises ..................................................................... 19
Learning Unit 4: Network Addressing ...................................................................... 20
1 Introduction ...................................................................................................... 20
2 Recommended Additional Reading .................................................................. 20
3 Activities and Revision Exercises ..................................................................... 21
Learning Unit 5: Internet Collaboration .................................................................... 22
1 Introduction ...................................................................................................... 22
2 Recommended Additional Reading .................................................................. 22
3 Activities and Revision Exercises ..................................................................... 22
Learning Unit 6: Internet of Things (IoT) .................................................................. 23
1 Introduction ...................................................................................................... 23
2 Recommended Additional Reading .................................................................. 23
3 Activities and Revision Exercises ..................................................................... 24
Learning Unit 7: Introduction to HTML, JavaScript, and PHP .................................. 25
1 Introduction ...................................................................................................... 25
2 Recommended Additional Reading .................................................................. 25
3 Activities and Revision Exercises ..................................................................... 25
Learning Unit 8: Computer Network Security ........................................................... 26
1 Introduction ...................................................................................................... 26
2 Recommended Additional Reading .................................................................. 26
3 Activities and Revision Exercises ..................................................................... 27
Chapter 1: The Internet ........................................................................................... 29
1 Introduction and History of the Internet ............................................................. 29
2 Evolution .......................................................................................................... 32
3 Advantages of the Internet ............................................................................... 44
4 Disadvantages of the Internet........................................................................... 46
5 The World Wide Web (WWW) .......................................................................... 47
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6 Web Pages ...................................................................................................... 51
7 Web Browser.................................................................................................... 55
8 Search Engines ................................................................................................ 63
9 Websites .......................................................................................................... 67
10
E-commerce ................................................................................................. 70
Chapter 2: Reference Models .................................................................................. 78
1 Introduction to reference models ...................................................................... 78
2 Open System Interface (OSI) Model ................................................................. 78
3 TCP/IP Model ................................................................................................... 81
4 Internet Protocols ............................................................................................. 82
5 Internet Services .............................................................................................. 88
6 Internet Connectivity......................................................................................... 91
7 Connection Types ............................................................................................ 92
8 Wireless Communication — Internet ................................................................ 96
Chapter 3: Network Addressing ..............................................................................105
1 What is Network? ............................................................................................105
2 Internet Protocol Address and Addressing ......................................................106
3 Binary Representation .....................................................................................109
4 IPv6 — Overview ............................................................................................120
5 Transition from IPv4 to IPv6 ............................................................................128
6 Future of IPv6..................................................................................................130
7 Network Services ............................................................................................131
8 Internet Domain Name System .......................................................................141
9 Domain Name System Architecture.................................................................143
10
DNS Working ...............................................................................................147
Chapter 4: Internet Collaboration............................................................................148
1 Internet Collaboration Overview ......................................................................148
2 Mailing List ......................................................................................................152
3 Usenet Newsgroup ..........................................................................................154
4 Online Education .............................................................................................159
5 Social Networking ...........................................................................................161
Chapter 5: Internet of Things ..................................................................................163
1 Internet of Things (IoT) — Overview ................................................................163
2 Internet of Things — Hardware .......................................................................165
3 Internet of Things — Software .........................................................................167
4 Internet of Things — Technology and Protocols ..............................................169
5 Internet of Things — Common Uses ...............................................................170
Chapter 6: Data Communication and Computer Network .......................................173
1 Classification of Computer Networks ...............................................................173
2 Computer Network Devices — Hub, Switch, Router, Bridges ..........................174
3 Computer Network Types ................................................................................175
4 Network LAN Technologies .............................................................................178
5 Computer Network Topologies ........................................................................180
Chapter 7: Computer Network Security ..................................................................186
1 Introduction .....................................................................................................186
2 Cryptography...................................................................................................187
3 Internet Security ..............................................................................................188
4 Threats ............................................................................................................188
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5 Email Phishing ................................................................................................189
6 Data Encryption...............................................................................................189
7 Digital Signature ..............................................................................................191
8 Firewall Security ..............................................................................................193
Chapter 8: The Web and Web Languages .............................................................194
1 What is WWW? ...............................................................................................194
2 What is HTTP? ................................................................................................194
3 What is Website? ............................................................................................194
4 What is Web Server? ......................................................................................195
5 What is W3C? .................................................................................................195
6 Web — How it Works? ....................................................................................195
7 Web — Browser Types ...................................................................................197
8 Web — Server Types ......................................................................................198
9 Introduction to Web Languages .......................................................................200
10
Cascading Style Sheet ................................................................................205
11
JavaScript ....................................................................................................210
12
Hypertext Pre-processor (PHP) ...................................................................224
Bibliography ...........................................................................................................227
Intellectual Property .............................................................................................230
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Using this Manual
This manual has been developed to meet the specific objectives of the module, and
uses a number of different sources. It functions as a stand-alone resource for this
module and no prescribed textbook or material is therefore required. There may,
however, be occasions when additional readings are also recommended to
supplement the information provided. Where these are specified, please ensure that
you engage with the reading as indicated.
Various activities and revision questions are included in the learning units of this
manual. These are designed to help you to engage with the subject matter as well as
to help you prepare for your assessments.
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Introduction
Internet Fundamentals serves as an introduction to networks, the World Wide Web
(WWW) and the role and function of the Internet as a communication medium and
source of information. You will be introduced to important network protocols and
learn about their functions.
Furthermore you will learn about the different elements that comes with the Internet
for example netiquette, security and much more. The role of the Internet has
changed very quickly over the last decade or so and you should be aware of the
implications. The role of social media, cloud computing and the implications of this.
In all aspects you will look at how the Internet and business are related, and work on
the premise of what the influence of the Internet and related developments are on the
business world.
The following main concepts are addressed in this module:








The Internet;
Reference Models;
Networks: Systems, Servers, Devices and Topologies;
Network Addressing;
Internet Collaboration;
Internet of Things (IoT);
Introduction to HTML, JavaScript and PHP;
Computer Network Security.
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Module Resources
Prescribed Book
for this Module
Software
Requirement
Recommended
Additional
Reading
Faculty of ICT. 2017. Internet Fundamentals. Module Manual.
Independent Institute of Education.
Web browsers
The following titles include information related to this module and
may be consulted as additional resources. Please note, however,
that you will not be tested on any content from these titles.
IoT Council. 2016. Internet of Things. Available at
http://www.theInternetofthings.eu/ [Date Accessed: 16 January
2017]
Internet Society. 2017. History of the Internet. Available at:
https://www.Internetsociety.org/Internet/what-Internet/historyInternet?gclid=Cj0KEQiAuJXFBRDirIGnpZLEN4BEiQAqV0KGtXcW-ult0g8axWrFcPEgUxrOUOYNjn94ez76aynWsaAhII8P8HAQ [Date
Accessed: 16 January 2017]
NetworkWorld. 2009. The evolution of the Internet. Available at:
http://www.networkworld.com/article/2870267/lan-wan/theevolution-of-the-Internet.html [Date Accessed: 16 January 2017]
Web Services Explained. Available at: http://www.servicearchitecture.com/articles/webservices/web_services_explained.html [Date Accessed: 16
January 2017]
The search Engine List. Available at:
http://www.thesearchenginelist.com/ [Date Accessed: 16 January
2017]
Reference Models in Communication Networks. Available at:
http://www.studytonight.com/computer-networks/referencemodels [Date Accessed: 16 January 2017]
OSI Seven Layers Model Explained with Examples. Available at:
http://www.studytonight.com/computer-networks/referencemodels [Date Accessed: 16 January 2017]
Networking tutorials for Beginners: Get Your Basics Right.
Available at:
https://blog.udemy.com/networking-tutorials-for-beginners/ [Date
Accessed: 16 January 2017]
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How TCP/IP Works. Available ate:
https://technet.microsoft.com/enus/library/cc786128(v=ws.10).aspx [Date Accessed: 16 January
2017]
TCP/IP Tools and Settings:
https://technet.microsoft.com/enus/library/cc786724(v=ws.10).aspx [Date Accessed: 16 January
2017]
TCP/IP Protocol Architecture. Available at:
https://technet.microsoft.com/en-us/library/cc958821.aspx [Date
Accessed: 16 January 2017]
Subnetting. Available at: https://technet.microsoft.com/enus/library/cc958834.aspx [Date Accessed: 16 January 2017]
Internet is All about Collaboration. Available at:
https://www.Internetsociety.org/blog/techmatters/2015/04/Internet-all-about-collaboration [Date Accessed:
16 January 2017]
Internet Collaboration. Available at:
http://www.Internetcollaboration.org/ [Date Accessed: 16 January
2017]
Internet of Things. Available at:
http://www.cisco.com/c/en/us/solutions/Internet-ofthings/overview.html [Date Accessed: 16 January 2017]
The Internet of Things is Far Bigger than Anyone Realised.
Available at: https://www.wired.com/insights/2014/11/theInternet-of-things-bigger/ [Date Accessed: 16 January 2017]
An Internet of Things: Examples. Available at:
http://www.postscapes.com/Internet-of-things-examples/[Date
Accessed: 16 January 2017]
HTML Basics, Available at:
http://www.htmlgoodies.com/primers/html/article.php/3478131
[Date Accessed: 16 January 2017]
Starting with HTML + CSS. Available at:
https://www.w3.org/Style/Examples/011/firstcss.en.html [Date
Accessed: 16 January 2017]
JavaScript for the Total Non-Programmer. Available at:
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http://www.webteacher.com/javascript/ [Date Accessed: 16
January 2017]
A Simple Tutorial – Manual. Available at:
http://php.net/manual/en/tutorial.php [Date Accessed: 16
January 2017]
SANS. 2017. Network Security. Available at:
https://www.sans.org/network-security/#free [Date Accessed: 16
January 2017]
Computer Security Threats. Available at:
https://www.webroot.com/za/en/home/resources/articles/pcsecurity/computer-security-threats [Date Accessed: 16 January
2017]
The 10 Most Common Security Threats Explained. Available at:
http://blogs.cisco.com/smallbusiness/the-10-most-commonsecurity-threats-explained [Date Accessed: 16 January 2017]
Common Threats to be Aware of. Available at:
https://www.getcybersafe.gc.ca/cnt/rsks/cmmn-thrts-en.aspx
[Date Accessed: 16 January 2017]
How Encryption Work. Available at:
http://computer.howstuffworks.com/encryption.htm [Date
Accessed: 16 January 2017]
The Beginner’s Guide to Encryption. Available at:
http://lifehacker.com/a-beginners-guide-to-encryption-what-it-isand-how-to-1508196946[Date Accessed: 16 January 2017]
Digital and Web
Resources
Firewall Security. Available at:
http://www.cisco.com/c/en/us/products/security/firewalls/what-isa-firewall.html [Date Accessed: 16 January 2017]
Additional digital resources are also available for this module.
Please log onto the Student Portal, and follow the links to
‘Supplementary Digital Material’ to source the following.
Some useful web links:
SANS. 2017. Network Security. Available at:
https://www.sans.org/network-security/#free
IoT Council. 2016. Internet of Things. Available at
http://www.theInternetofthings.eu/ [Date Accessed: 16 January
2017]
© The Independent Institute of Education (Pty) Ltd 2017
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Module Purpose
The purpose of this module is to provide knowledge of the role and function of the
Internet as a communication medium and source of information by covering
important network protocols and their function.
Module Outcomes
MO1
MO2
MO3
MO4
MO5
Demonstrate an understanding of the important protocols and concepts
and logical network structure as they relate to the Internet and the World
Wide Web (WWW).
Demonstrate an understanding of the different server in modern networks
especially as they relate to Web Server platforms.
Demonstrate the understanding necessary to identify and solve security
threats.
Demonstrate the ability to identify and solve Internet problems using
applicable tools.
Demonstrate understanding of the legal environment and ethical issues in
relation to the Internet.
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Module Pacer
Code INFU112
Learning Unit 1
INFU112
Sessions: 1—5
Related Outcomes:
MO1
MO2
MO3
MO4
MO5
Learning Unit 2
INFU112
Sessions: 6—10
Related Outcomes:
MO1
MO2
MO3
MO4
MO5
Learning Unit 3
INFU112
Sessions: 11—15
Related Outcomes:
MO1
MO2
MO3
MO4
MO5
Learning Unit 4
INFU112
Sessions: 16—20
Related Outcomes:
MO1
MO2
MO3
MO4
MO5
Contact hours
40
Theme: The Internet
Learning content:

Introduction to the Internet;

Evolution of the Internet;

Advantages and Disadvantages of
the Internet;

The World Wide Web;

Web Pages;

The Web Browser;

Search Engines;

Websites.
Theme: Reference Models
Learning content:

The OSI reference model;

The TCP/IP model;

Internet Protocols;

Internet Services;

Web services;

Internet Connectivity.
Credits 10
Notes on this LU
Assessed in:

Assignment;

Test;

Examination.
Theme: Networks: Systems, Servers,
Devices and Topologies
Learning content:

Classification of Computer
Networks;

Computer Network Devices;

Computer Network Types;

Network LAN technologies;

Computer Networks Topologies.
Notes on this LU
Theme: Network Addressing
Learning content:

The Network and IPv4 Overview;

Addressing and Addressing Modes;

Hieratical Addressing Scheme;

IPv4 Classes;

IPv4 Sub-netting;

IPV6 Overview and Features;

IPv6 Addressing Modes;

Future of IPv6;

Network Services;

Internet Domain Name System
(DNS).
Notes on this LU
Assessed in:

Assignment;

Test;

Examination.
© The Independent Institute of Education (Pty) Ltd 2017
Notes on this LU
Assessed in:

Assignment;

Test;

Examination.
Assessed in:

Examination.
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Learning Unit 5
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Sessions: 21—25
Related Outcomes:
MO1
MO2
MO3
MO4
MO5
Learning Unit 6
INFU112
Sessions: 26—30
Related Outcomes:
MO1
MO2
MO3
MO4
MO5
Learning Unit 7
INFU112
Sessions: 31—35
Related Outcomes:
MO1
MO2
MO3
MO4
MO5
Learning Unit 8
INFU112
Sessions: 36—40
Related Outcomes:
MO1
MO2
MO3
MO4
MO5
INFU112
Theme: Internet Collaboration
Learning content:

Online chatting;

Newsgroups;

Web-based and Online Education;

Social Networking.
Notes on this LU
Assessed in:

Assignment;

Examination.
Theme: Internet of Things (IoT)
Learning content:

Overview and Key Features of IoT;

Advantages and Disadvantages of
IoT;

Internet of Things Hardware;

Internet of Things Software;

Internet of Things Common Uses.
Notes on this LU
Assessed in:

Examination.
Theme: Introduction to HTML,
JavaScript and PHP
Learning content:

Hyper Text Mark-up Language
(HTML);

Cascading Style Sheets;

JavaScript;

Hypertext Pre-processor (PHP).
Notes on this LU
Theme: Computer Network Security
Learning content:

Security Threats Categories;

Encryption;

Internet security;

Types of Data Encryption;

Digital Signature;

Firewall Security
Notes on this LU
Assessed in:

Examination.
© The Independent Institute of Education (Pty) Ltd 2017
Assessed in:

Examination.
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Assessments
Integrated Curriculum Engagement (ICE)
Minimum number of ICE activities to complete
Weighting towards the final module mark
Assignments/ Projects
Weighting
Duration
Submit after
Learning Units covered
Assignment
25%
10 hours
LU4
LU1—4
Tests/ Examination
Weighting
Duration
Total marks
Open/ closed book
Resources required
Learning Units covered
Test
30%
1 hour
60
Closed book
Basic calculator
LU1—4
Assessment Preparation Guidelines
Format of the
Assessment
(The Focus/ Approach/
Objectives)
Assignment
Refer to the assignment
for this information.
Test
Refer to the assessment
brief for this information.
Examination
Refer to the assessment
brief for this information.
© The Independent Institute of Education (Pty) Ltd 2017
4
10%
Examination
35%
2 hours
120
Closed book
Basic calculator
All
Preparation Hints
(How to Prepare,
Resources to Use, etc.)
Refer to the assignment for
this information.
Refer to the assessment
brief for this information.
Refer to the assessment
brief for this information.
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Learning Unit 1: The Internet
Material used for this learning unit:

Prescribed text: this manual – chapter 1
How to prepare for this Learning Unit:

Ensure that you are able to access all the material
used for this Learning Unit;

Prepare questions on areas about which you are
uncertain. Have these questions ready for
discussions and activities;

Read and review the activities and revision exercises
and seek to understand what is required and
expected of you;

Search the Internet and visit your library to conduct
research on the concepts covered in this Learning
Unit.
1
My Notes
Introduction
Before you can really understand the Internet, its impact and
the magic of it, you need to understand where it all started and
how it has grown over the last number of years.
In this learning unit you will be taking a brief look at the history
and background of the Internet as well as the role and need for
it and how it works. Similarly, the WWW, websites, webpages,
search engines and e-commerce will be explored in this
learning unit. For most concepts, the learning uses covers the
related history or the evolution, the architecture, functions and
explain how the concepts work.
2
Recommended Additional Reading
IoT Council. 2016. Internet of Things. Available at
http://www.theInternetofthings.eu/ [Date Accessed: 16 January
2017]
Internet Society. 2017. History of the Internet. Available at:
https://www.Internetsociety.org/Internet/what-Internet/historyInternet?gclid=Cj0KEQiAuJXFBRDirIGnpZLEN4BEiQAqV0KGtXcW-ult0g8axWrFcPEgUxrOUOYNjn94ez76aynWsaAhII8P8HAQ [Date
Accessed: 16 January 2017]
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NetworkWorld. 2009. The evolution of the Internet. Available
at: http://www.networkworld.com/article/2870267/lan-wan/theevolution-of-the-Internet.html [Date Accessed: 16 January
2017]
Web Services Explained. Available at: http://www.servicearchitecture.com/articles/webservices/web_services_explained.html [Date Accessed: 16
January 2017]
The search Engine List. Available at:
http://www.thesearchenginelist.com/ [Date Accessed: 16
January 2017]
3
Activities and Revision Exercises
Refer to the workbook for this information.
© The Independent Institute of Education (Pty) Ltd 2017
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Learning Unit 2: Reference Models
Material used for this learning unit:

Prescribed text: this manual – Chapter 2
How to prepare for this Learning Unit:

Ensure that you are able to access all the material
used for this Learning Unit;

Prepare questions on areas about which you are
uncertain. Have these questions ready for
discussions and activities;

Read and review the activities and revision exercises
and seek to understand what is required and
expected of you;
Search the Internet and visit your library to conduct
research on the concepts covered in this Learning Unit.
1
My Notes
Introduction
This learning unit introduces you to the different types of
computer/ network reference models. The learning unit first
addresses the Open System Interface (OSI) model. The
activities and the functions of this model are briefly explained.
Secondly, the TCP/IP models is discussed. The activities and
the functions of this model are briefly explained. The learning
unit introduces you to the Internet protocols and Internet
services. Internet connection and the connection types are
also discussed.
2
Recommended Additional Reading
Reference Models in Communication Networks. Available at:
http://www.studytonight.com/computer-networks/referencemodels
OSI Seven Layers Model Explained with Examples. Available
at:
http://www.studytonight.com/computer-networks/referencemodels
3
Activities and Revision Exercises
Refer to the workbook for this information.
© The Independent Institute of Education (Pty) Ltd 2017
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Learning Unit 3: Networks: Systems, Devices,
Topologies and Technologies
Material used for this learning unit:

Prescribed text: this manual – Chapter 6
How to prepare for this Learning Unit:

Ensure that you are able to access all the material
used for this Learning Unit;

Prepare questions on areas about which you are
uncertain. Have these questions ready for
discussions and activities;

Read and review the activities and revision exercises
and seek to understand what is required and
expected of you;

Search the Internet and visit your library to conduct
research on the concepts covered in this Learning
Unit.
1
My Notes
Introduction
A system of interconnected computers and computerised
peripherals, such as printers, are called computer networks.
This interconnection among computers facilitates information
sharing among them. Computers may connect to each other
by either wired or wireless media.
In this learning unit, you are introduced to the basic networking
concepts and topics and will explore network devices,
topologies, and technologies under the following topics:





Classification of Computer Networks;
Computer Network Devices;
Computer Network Types;
Network LAN technologies;
Computer Networks Topologies.
2
Recommended Additional Reading
Networking tutorials for Beginners: Get Your Basics Right.
Available at:
https://blog.udemy.com/networking-tutorials-for-beginners/
3
Activities and Revision Exercises
Refer to the workbook for this information.
© The Independent Institute of Education (Pty) Ltd 2017
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Learning Unit 4: Network Addressing
Material used for this learning unit:

Prescribed text: this manual – Chapter 3
How to prepare for this Learning Unit:

Ensure that you are able to access all the material
used for this Learning Unit;

Prepare questions on areas about which you are
uncertain. Have these questions ready for
discussions and activities;

Read and review the activities and revision exercises
and seek to understand what is required and
expected of you;

Search the Internet and visit your library to conduct
research on the concepts covered in this Learning
Unit.
1
My Notes
Introduction
In this learning unit, you will be introduced to network
addressing. The concept of ‘network’ and why network
addressing is an essential part of network design and
configuration is addressed. The learning unit will explore the
IPv4 and briefly IPv6 concepts including, host addressing,
types of addressing modes, addressing schemes, address
classes, subnettings and the VLSM. The Learning unit will
discuss the different types of network services and Internet
technologies. A detail section unpacking this of the DNS
service is included in this learning unit.
2
Recommended Additional Reading
How TCP/IP Works. Available ate:
https://technet.microsoft.com/enus/library/cc786128(v=ws.10).aspx
TCP/IP Tools and Settings:
https://technet.microsoft.com/enus/library/cc786724(v=ws.10).aspx
TCP/IP Protocol Architecture. Available at:
https://technet.microsoft.com/en-us/library/cc958821.aspx
Subnetting. Available at: https://technet.microsoft.com/enus/library/cc958834.aspx
© The Independent Institute of Education (Pty) Ltd 2017
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Activities and Revision Exercises
Refer to the workbook for this information.
© The Independent Institute of Education (Pty) Ltd 2017
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Learning Unit 5: Internet Collaboration
Material used for this learning unit:

Prescribed text: this manual – Chapter 4
How to prepare for this Learning Unit:

Ensure that you are able to access all the material
used for this Learning Unit;

Prepare questions on areas about which you are
uncertain. Have these questions ready for
discussions and activities;

Read and review the activities and revision exercises
and seek to understand what is required and
expected of you;

Search the Internet and visit your library to conduct
research on the concepts covered in this Learning
Unit.
1
Introduction
2
Recommended Additional Reading
My Notes
Internet is All about Collaboration. Available at:
https://www.Internetsociety.org/blog/techmatters/2015/04/Internet-all-about-collaboration
Internet Collaboration. Available at:
http://www.Internetcollaboration.org/
3
Activities and Revision Exercises
Refer to the workbook for this information.
© The Independent Institute of Education (Pty) Ltd 2017
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Learning Unit 6: Internet of Things (IoT)
Material used for this learning unit:

Prescribed text: this manual – Chapter 5
How to prepare for this Learning Unit:

Ensure that you are able to access all the material
used for this Learning Unit;

Prepare questions on areas about which you are
uncertain. Have these questions ready for
discussions and activities;

Read and review the activities and revision exercises
and seek to understand what is required and
expected of you;

Search the Internet and visit your library to conduct
research on the concepts covered in this Learning
Unit.
1
My Notes
Introduction
Internet of Things (IoT) systems allow users to achieve deeper
automation, analysis and integration within a system. IoT
utilises existing and emerging technology for sensing,
networking and robotics. Its new and advanced elements bring
major changes in the delivery of products, goods and services;
and the social, economic and political impact of those
changes.
This learning unit will explore the fundamental concepts of IoT,
including,
 The key features;
 Advantages and disadvantages;
 The hardware and software involved;
 Technologies and Protocols;
 Common uses.
2
Recommended Additional Reading
Internet of Things. Available at:
http://www.cisco.com/c/en/us/solutions/Internet-ofthings/overview.html
The Internet of Things is Far Bigger than Anyone Realised.
Available at: https://www.wired.com/insights/2014/11/theInternet-of-things-bigger/
An Internet of Things: Examples. Available at:
http://www.postscapes.com/Internet-of-things-examples/
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Activities and Revision Exercises
Refer to the workbook for this information.
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Learning Unit 7: Introduction to HTML, JavaScript,
and PHP
Material used for this learning unit:

Prescribed text: this manual – Chapter 8
How to prepare for this Learning Unit:

Ensure that you are able to access all the material
used for this Learning Unit;

Prepare questions on areas about which you are
uncertain. Have these questions ready for
discussions and activities;

Read and review the activities and revision exercises
and seek to understand what is required and
expected of you;

Search the Internet and visit your library to conduct
research on the concepts covered in this Learning
Unit.
1
My Notes
Introduction
In this learning unit, you will be introduced to some of the
common web technologies and their languages. The learning
unit will show you the basic coding and programming
necessary for you to be able to recognise the language and
learn what the language involves.
2
Recommended Additional Reading
HTML Basics, Available at:
http://www.htmlgoodies.com/primers/html/article.php/3478131
Starting with HTML + CSS. Available at:
https://www.w3.org/Style/Examples/011/firstcss.en.html
JavaScript for the Total Non-Programmer. Available at:
http://www.webteacher.com/javascript/
A Simple Tutorial – Manual. Available at:
http://php.net/manual/en/tutorial.php
3
Activities and Revision Exercises
Refer to the workbook for this information.
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Learning Unit 8: Computer Network Security
Material used for this learning unit:

Prescribed text: this manual – Chapter 7
How to prepare for this Learning Unit:

Ensure that you are able to access all the material
used for this Learning Unit;

Prepare questions on areas about which you are
uncertain. Have these questions ready for
discussions and activities;

Read and review the activities and revision exercises
and seek to understand what is required and
expected of you;

Search the Internet and visit your library to conduct
research on the concepts covered in this Learning
Unit.
My Notes
Introduction
1
No technique in the present world can provide 100% security.
But steps can be taken to secure data while it travels in an
unsecured network or Internet.
This learning unit introduces you to the basic concepts of
computer network security. The learning unit takes you through
the discussion of essential concepts, including,







2
Cryptography;
Internet security;
Threats;
Email phishing;
Data encryption;
Digital signature;
Firewall security.
Recommended Additional Reading
SANS. 2017. Network Security. Available at:
https://www.sans.org/network-security/#free
Computer Security Threats. Available at:
https://www.webroot.com/za/en/home/resources/articles/pcsecurity/computer-security-threats
The 10 Most Common Security Threats Explained. Available
at: http://blogs.cisco.com/smallbusiness/the-10-most-commonsecurity-threats-explained
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Common Threats to be Aware of. Available at:
https://www.getcybersafe.gc.ca/cnt/rsks/cmmn-thrts-en.aspx
How Encryption Work. Available at:
http://computer.howstuffworks.com/encryption.htm
The Beginner’s Guide to Encryption. Available at:
http://lifehacker.com/a-beginners-guide-to-encryption-what-itis-and-how-to-1508196946
Firewall Security. Available at:
http://www.cisco.com/c/en/us/products/security/firewalls/whatis-a-firewall.html
3
Activities and Revision Exercises
Refer to the workbook for this information.
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INTERNET FUNDAMENTALS
MODULE CONTENT 2017
Notes:
The introduction, history and evolution of the Internet sections in this manual is
adapted
with
permission
from
the
Internet
Society
website
at
http://www.internetsociety.org/internet/what-internet/history-internet/brief-historyinternet
The content in the sections listed below is adapted with permission from the
TutorialsPoint website and resources available at http://www.tutorialspoint.com







Reference Models;
Networks: Systems, Servers, Devices and Topologies;
Network Addressing;
Internet Collaboration;
Internet of Things (IoT);
Introduction to HTML, JavaScript and PHP;
Computer Network Security.
This manual enjoys copyright under the Berne Convention. In terms of the Copyright
Act, no 98 of 1978, no part of this manual may be reproduced or transmitted in any
form or by any means, electronic or mechanical, including photocopying, recording or
by any other information storage and retrieval system without permission in writing
from the proprietor.
The Independent Institute of Education (Pty) Ltd is
registered with the Department of Higher Education and
Training as a private higher education institution under the
Higher Education Act, 1997 (reg. no. 2007/HE07/002).
Company registration number: 1987/004754/07.
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Chapter 1: The Internet
The introduction, history and evolution of the Internet sections
in this manual is adapted with permission from the Internet
Society
website
at:
[Online].
Available
at:
http://www.Internetsociety.org/Internet/what-Internet/historyInternet/brief-history-Internet [Accessed 23 January 2017].
1
Introduction and History of the
Internet
The Internet has revolutionised the computer and
communications world like nothing before. The invention of the
telegraph, telephone, radio and computer set the stage for this
unprecedented integration of capabilities. The Internet is at
once a world-wide broadcasting capability, a mechanism for
information dissemination and a medium for collaboration and
interaction between individuals and their computers without
regard for geographic location.
The first recorded description of the social interactions that
could be enabled through networking was a series of memos
written by J.C.R. Licklider of MIT in August 1962 discussing his
"Galactic Network" concept. He envisioned a globally
interconnected set of computers through which everyone could
quickly access data and programs from any site. In spirit, the
concept was very much like the Internet of today. Licklider was
the first head of the computer research program at DARPA,
starting in October 1962. While at DARPA he convinced his
successors at DARPA, Ivan Sutherland, Bob Taylor and MIT
researcher Lawrence G. Roberts, of the importance of this
networking concept.
Leonard Kleinrock at MIT published the first paper on packet
switching theory in July 1961 and the first book on the subject
in 1964. Kleinrock convinced Roberts of the theoretical
feasibility of communications using packets rather than circuits,
which was a major step along the path towards computer
networking. The other key step was to make the computers
talk together. To explore this, in 1965 working with Thomas
Merrill, Roberts connected the TX-2 computer in Mass. to the
Q-32 in California with a low speed dial-up telephone line
creating the first (however small) wide-area computer network
ever built.
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The result of this experiment was the realisation that the timeshared computers could work well together, running programs
and retrieving data as necessary on the remote machine, but
that the circuit-switched telephone system was totally
inadequate for the job. Kleinrock's conviction of the need for
packet switching was confirmed.
In late 1966 Roberts went to DARPA to develop the computer
network concept and quickly put together his plan for the
"ARPANET", publishing it in 1967. At the conference where he
presented the paper, there was also a paper on a packet
network concept from the UK by Donald Davies and Roger
Scantlebury of NPL. Scantlebury told Roberts about the NPL
work as well as that of Paul Baran and others at RAND.
The RAND group had written a paper on packet switching
networks for secure voice in the military in 1964. It happened
that the work at MIT (1961—1967), at RAND (1962—1965)
and at NPL (1964—1967) had all proceeded in parallel without
any of the researchers knowing about the other work. The
word "packet" was adopted from the work at NPL and the
proposed line speed to be used in the ARPANET design was
upgraded from 2.4 kbps to 50 kbps.
In August 1968, after Roberts and the DARPA funded
community had refined the overall structure and specifications
for the ARPANET, an RFQ was released by DARPA for the
development of one of the key components, the packet
switches called Interface Message Processors (IMP's). The
RFQ was won in December 1968 by a group headed by Frank
Heart at Bolt Beranek and Newman (BBN). As the BBN team
worked on the IMP's with Bob Kahn playing a major role in the
overall ARPANET architectural design, the network topology
and economics were designed and optimised by Roberts
working with Howard Frank and his team at Network Analysis
Corporation, and the network measurement system was
prepared by Kleinrock's team at UCLA.
Due to Kleinrock's early development of packet switching
theory and his focus on analysis, design and measurement, his
Network Measurement Center at UCLA was selected to be the
first node on the ARPANET. All this came together in
September 1969 when BBN installed the first IMP at UCLA
and the first host computer was connected. Doug Engelbart's
project on "Augmentation of Human Intellect" (which included
NLS, an early hypertext system) at Stanford Research Institute
(SRI) provided a second node.
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SRI supported the Network Information Center, led by
Elizabeth (Jake) Feinler and including functions such as
maintaining tables of host name to address mapping as well as
a directory of the RFC's.
One month later, when SRI was connected to the ARPANET,
the first host-to-host message was sent from Kleinrock's
laboratory to SRI. Two more nodes were added at UC Santa
Barbara and University of Utah. These last two nodes
incorporated application visualisation projects, with Glen Culler
and Burton Fried at UCSB investigating methods for display of
mathematical functions using storage displays to deal with the
problem of refresh over the net and Robert Taylor and Ivan
Sutherland at Utah investigating methods of 3D
representations over the net. Thus, by the end of 1969, four
host computers were connected together into the initial
ARPANET and the budding Internet was off the ground. Even
at this early stage, it should be noted that the networking
research incorporated both work on the underlying network
and work on how to utilise the network. This tradition continues
to this day.
Computers were added quickly to the ARPANET during the
following years and work proceeded on completing a
functionally complete Host-to-Host protocol and other network
software. In December 1970 the Network Working Group
(NWG), working under S. Crocker, finished the initial
ARPANET Host-to-Host protocol, called the Network Control
Protocol (NCP). As the ARPANET sites completed
implementing NCP during the period 1971—1972, the network
users finally could begin to develop applications.
In October 1972, Kahn organised a large, very successful
demonstration of the ARPANET at the International Computer
Communication Conference (ICCC). This was the first public
demonstration of this new network technology to the public. It
was also in 1972 that the initial "hot" application, electronic
mail, was introduced. In March Ray Tomlinson at BBN wrote
the basic email message send and read software, motivated
by the need of the ARPANET developers for an easy
coordination mechanism. In July, Roberts expanded its utility
by writing the first email utility program to list, selectively read,
file, forward and respond to messages. From there email took
off as the largest network application for over a decade. This
was a harbinger of the kind of activity we see on the World
Wide Web today, namely, the enormous growth of all kinds of
"people-to-people" traffic.
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Evolution
The concept of Internet was originated in 1969 and has
undergone several technological and Infrastructural changes
as discussed below:

The origin of Internet devised from the concept of
Advanced
Research
Project
Agency
Network
(ARPANET);

ARPANET was developed by United States Department
of Defense;

Basic purpose of ARPANET was to provide
communication among the various bodies of
government;

Initially, there were only four nodes, formally called
Hosts;

In 1972, the ARPANET spread over the globe with
23 nodes located at different countries and, thus,
became known as Internet;

By the time, with the invention of new technologies such
as TCP/IP protocols, DNS, WWW, browsers, scripting
languages, etc., Internet provided a medium to publish
and access information over the web.
The original ARPANET grew into the Internet. Internet was
based on the idea that there would be multiple independent
networks of rather arbitrary design, beginning with the
ARPANET as the pioneering packet switching network, but
soon to include packet satellite networks, ground-based packet
radio networks and other networks. The Internet as we now
know it embodies a key underlying technical idea, namely that
of open architecture networking. In this approach, the choice of
any individual network technology was not dictated by a
particular network architecture, but rather could be selected
freely by a provider and made to interwork with the other
networks through a meta-level "Internetworking Architecture".
Up until that time there was only one general method for
federating networks. This was the traditional circuit switching
method where networks would interconnect at the circuit level,
passing individual bits on a synchronous basis along a portion
of an end-to-end circuit between a pair of end locations. Recall
that Kleinrock had shown in 1961 that packet switching was a
more efficient switching method. Along with packet switching,
special purpose interconnection arrangements between
networks were another possibility.
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While there were other limited ways to interconnect different
networks, they required that one be used as a component of
the other, rather than acting as a peer of the other in offering
end-to-end service.
In an open-architecture network, the individual networks may
be separately designed and developed and each may have its
own unique interface which it may offer to users and/ or other
providers, including other Internet providers. Each network can
be designed in accordance with the specific environment and
user requirements of that network. There are generally no
constraints on the types of network that can be included or on
their geographic scope, although certain pragmatic
considerations will dictate what makes sense to offer.
The idea of open-architecture networking was first introduced
by Kahn shortly after having arrived at DARPA in 1972. This
work was originally part of the packet radio program, but
subsequently became a separate program in its own right. At
the time, the program was called "Internetting". Key to making
the packet radio system work was a reliable end-end protocol
that could maintain effective communication in the face of
jamming and other radio interference or withstand intermittent
blackout such as caused by being in a tunnel or blocked by the
local terrain. Kahn first contemplated developing a protocol
local only to the packet radio network, since that would avoid
having to deal with the multitude of different operating systems
and continuing to use NCP.
However, NCP did not have the ability to address networks
(and machines) further downstream than a destination IMP on
the ARPANET and thus some change to NCP would also be
required. (The assumption was that the ARPANET was not
changeable in this regard). NCP relied on ARPANET to
provide end-to-end reliability. If any packets were lost, the
protocol (and presumably any applications it supported) would
come to a grinding halt. In this model NCP had no end-end
host error control, since the ARPANET was to be the only
network in existence and it would be so reliable that no error
control would be required on the part of the hosts. Thus, Kahn
decided to develop a new version of the protocol which could
meet the needs of an open-architecture network environment.
This protocol would eventually be called the Transmission
Control Protocol/ Internet Protocol (TCP/IP). While NCP
tended to act like a device driver, the new protocol would be
more like a communications protocol.
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Four ground rules were critical to Kahn's early thinking:

Each distinct network would have to stand on its own
and no internal changes could be required to any such
network to connect it to the Internet;

Communications would be on a best effort basis. If a
packet did not make it to the final destination, it would
shortly be retransmitted from the source;

Black boxes would be used to connect the networks;
these would later be called gateways and routers. There
would be no information retained by the gateways about
the individual flows of packets passing through them,
thereby keeping them simple and avoiding complicated
adaptation and recovery from various failure modes;

There would be no global control at the operations level.
Other key issues that needed to be addressed were:

Algorithms to prevent lost packets from permanently
disabling communications and enabling them to be
successfully retransmitted from the source;

Providing for host-to-host "pipelining" so that multiple
packets could be en-route from source to destination at
the discretion of the participating hosts, if the
intermediate networks allowed it;

Gateway functions to allow it to forward packets
appropriately. This included interpreting IP headers for
routing, handling interfaces, breaking packets into
smaller pieces if necessary, etc.;

The need for end-end checksums, reassembly of
packets from fragments and detection of duplicates, if
any;

The need for global addressing;

Techniques for host-to-host flow control;

Interfacing with the various operating systems;

There were also other concerns, such as implementation
efficiency, Internetwork performance, but these were
secondary considerations at first.
Kahn began work on a communications-oriented set of
operating system principles while at BBN and documented
some of his early thoughts in an internal BBN memorandum
entitled "Communications Principles for Operating Systems".
At this point he realised it would be necessary to learn the
implementation details of each operating system to have a
chance to embed any new protocols in an efficient way.
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Thus, in the spring of 1973, after starting the Internetting effort,
he asked Vint Cerf (then at Stanford) to work with him on the
detailed design of the protocol. Cerf had been intimately
involved in the original NCP design and development and
already had the knowledge about interfacing to existing
operating systems. So armed with Kahn's architectural
approach to the communications side and with Cerf's NCP
experience, they teamed up to spell out the details of what
became TCP/IP.
The give and take was highly productive and the first written
version of the resulting approach was distributed at a special
meeting of the International Network Working Group (INWG)
which had been set up at a conference at Sussex University in
September 1973. Cerf had been invited to chair this group and
used the occasion to hold a meeting of INWG members who
were heavily represented at the Sussex Conference.
Some basic approaches emerged from this collaboration
between Kahn and Cerf:

Communication between two processes would logically
consist of a very long stream of bytes (they called them
octets). The position of any octet in the stream would be
used to identify it;

Flow control would be done by using sliding windows
and acknowledgments (acks). The destination could
select when to acknowledge and each ack returned
would be cumulative for all packets received to that
point;

It was left open as to exactly how the source and
destination would agree on the parameters of the
windowing to be used. Defaults were used initially;

Although Ethernet was under development at Xerox
PARC at that time, the proliferation of LANs was not
envisioned at the time, much less PCs and workstations.
The original model was national level networks like
ARPANET of which only a relatively small number were
expected to exist. Thus a 32-bit IP address was used of
which the first eight bits signified the network and the
remaining 24 bits designated the host on that network.
This assumption, that 256 networks would be sufficient
for the foreseeable future, was clearly in need of
reconsideration when LANs began to appear in the late
1970s.
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The original Cerf/ Kahn paper on the Internet described one
protocol, called TCP, which provided all the transport and
forwarding services in the Internet. Kahn had intended that the
TCP protocol support a range of transport services, from the
totally reliable sequenced delivery of data (virtual circuit model)
to a datagram service in which the application made direct use
of the underlying network service, which might imply
occasional lost, corrupted or reordered packets. However, the
initial effort to implement TCP resulted in a version that only
allowed for virtual circuits.
This model worked fine for file transfer and remote login
applications, but some of the early work on advanced network
applications; in particular packet voice in the 1970s, made it
clear that in some cases packet losses should not be corrected
by TCP, but should be left to the application to deal with. This
led to a reorganisation of the original TCP into two protocols,
the simple IP which provided only for addressing and
forwarding of individual packets and the separate TCP, which
was concerned with service features such as flow control and
recovery from lost packets. For those applications that did not
want the services of TCP, an alternative called the User
Datagram Protocol (UDP) was added in order to provide direct
access to the basic service of IP.
A major initial motivation for both the ARPANET and the
Internet was resource sharing — for example allowing users
on the packet radio networks to access the time sharing
systems attached to the ARPANET. Connecting the two
together was far more economical that duplicating these very
expensive computers. However, while file transfer and remote
login (Telnet) were very important applications, electronic mail
has probably had the most significant impact of the innovations
from that era. Email provided a new model of how people
could communicate with each other and changed the nature of
collaboration, first in the building of the Internet itself (as is
discussed below) and later for much of society.
There were other applications proposed in the early days of
the Internet, including packet-based voice communication (the
precursor of Internet telephony), various models of file and disk
sharing, and early "worm" programs that showed the concept
of agents (and, of course, viruses). A key concept of the
Internet is that it was not designed for just one application, but
as a general infrastructure on which new applications could be
conceived, as illustrated later by the emergence of the World
Wide Web. It is the general purpose nature of the service
provided by TCP and IP that makes this possible.
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At the same time that the Internet technology was being
experimentally validated and widely used amongst a subset of
computer science researchers, other networks and networking
technologies were being pursued. The usefulness of computer
networking — especially electronic mail — demonstrated by
DARPA and Department of Defense contractors on the
ARPANET was not lost on other communities and disciplines,
so that by the mid-1970s computer networks had begun to
spring up wherever funding could be found for the purpose.
The U.S. Department of Energy (DoE) established MFENet for
its researchers in Magnetic Fusion Energy, whereupon DoE's
High Energy Physicists responded by building HEPNet. NASA
Space Physicists followed with SPAN and Rick Adrion, David
Farber, and Larry Landweber established CSNET for the
(academic and industrial) Computer Science community with
an initial grant from the U.S. National Science Foundation
(NSF). AT&T's free-wheeling dissemination of the UNIX
computer operating system spawned USENET, based on
UNIX' built-in UUCP communication protocols and in 1981 Ira
Fuchs and Greydon Freeman devised BITNET, which linked
academic mainframe computers in an "email as card images"
paradigm.
With the exception of BITNET and USENET, these early
networks (including ARPANET) were purpose-built — i.e. they
were intended for, and largely restricted to, closed
communities of scholars; there was hence little pressure for
the individual networks to be compatible and, indeed, they
largely were not. In addition, alternate technologies were being
pursued in the commercial sector, including XNS from Xerox,
DECNet and IBM's SNA. It remained for the British JANET
(1984) and U.S. NSFNET (1985) programs to explicitly
announce their intent to serve the entire higher education
community, regardless of discipline. Indeed, a condition for a
U.S. university to receive NSF funding for an Internet
connection was that "... the connection must be made
available to all qualified users on campus."
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In 1985, Dennis Jennings came from Ireland to spend a year at
NSF leading the NSFNET program. He worked with the
community to help NSF make a critical decision — that TCP/IP
would be mandatory for the NSFNET program. When Steve
Wolff took over the NSFNET program in 1986, he recognised
the need for a wide area networking infrastructure to support
the general academic and research community, along with the
need to develop a strategy for establishing such infrastructure
on a basis ultimately independent of direct federal funding.
Policies and strategies were adopted (see below) to achieve
that end.
NSF also elected to support DARPA's existing Internet
organisational infrastructure, hierarchically arranged under the
(then) Internet Activities Board (IAB). The public declaration of
this choice was the joint authorship by the IAB's Internet
Engineering and Architecture Task Forces and by NSF's
Network Technical Advisory Group of RFC 985 (Requirements
for Internet Gateways ), which formally ensured interoperability
of DARPA's and NSF's pieces of the Internet.
In addition to the selection of TCP/IP for the NSFNET program,
Federal agencies made and implemented several other policy
decisions which shaped the Internet of today:

Federal agencies shared the cost of common
infrastructure, such as trans-oceanic circuits. They also
jointly supported "managed interconnection points" for
interagency traffic; the Federal Internet Exchanges (FIXE and FIX-W) was built for this purpose and served as
models for the Network Access Points and "*IX" facilities
that are prominent features of today's Internet
architecture;

To coordinate this sharing, the Federal Networking
Council9 was formed. The FNC also cooperated with
other international organisations, such as RARE in
Europe, through the Coordinating Committee on
Intercontinental Research Networking, CCIRN, to
coordinate Internet support of the research community
worldwide;

This sharing and cooperation between agencies on the
Internet-related issues had a long history. An
unprecedented 1981 agreement between Farber, acting
for CSNET and the NSF, and DARPA's Kahn, permitted
CSNET traffic to share ARPANET infrastructure on a
statistical and no-metered-settlements basis;
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Subsequently, in a similar mode, the NSF encouraged its
regional (initially academic) networks of the NSFNET to
seek commercial, non-academic customers, expand their
facilities to serve them and exploit the resulting
economies of scale to lower subscription costs for all;
On the NSFNET Backbone — the national-scale
segment of the NSFNET — NSF enforced an
"Acceptable Use Policy" (AUP) which prohibited
Backbone usage for purposes "not in support of
Research and Education." The predictable (and
intended) result of encouraging commercial network
traffic at the local and regional level, while denying its
access to national-scale transport, was to stimulate the
emergence and/ or growth of "private", competitive, longhaul networks such as PSI, UUNET, ANS CO+RE and
(later) others. This process of privately-financed
augmentation for commercial uses was thrashed out
starting in 1988 in a series of NSF-initiated conferences
at Harvard's Kennedy School of Government on "The
Commercialization and Privatization of the Internet" —
and on the "com-priv" list on the net itself;
In 1988, a National Research Council committee, chaired
by Kleinrock and with Kahn and Clark as members,
produced a report commissioned by NSF titled "Towards
a National Research Network". This report was influential
on then Senator Al Gore and ushered in high speed
networks that laid the networking foundation for the
future information superhighway;
In 1994, a National Research Council report, again
chaired by Kleinrock (and with Kahn and Clark as
members again), Entitled "Realizing The Information
Future: The Internet and Beyond" was released. This
report, commissioned by NSF, was the document in
which a blueprint for the evolution of the information
superhighway was articulated and which has had a
lasting effect on the way to think about its evolution. It
anticipated the critical issues of intellectual property
rights, ethics, pricing, education, architecture and
regulation for the Internet;
NSF's privatisation policy culminated in April, 1995, with
the defunding of the NSFNET Backbone. The funds
thereby recovered were (competitively) redistributed to
regional networks to buy national-scale Internet
connectivity from the now numerous, private, long-haul
networks.
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The backbone had made the transition from a network built
from routers out of the research community (the "Fuzzball"
routers from David Mills) to commercial equipment. In its
8½ year lifetime, the Backbone had grown from six nodes with
56 kbps links to 21 nodes with multiple 45 Mbps links. It had
seen the Internet grow to over 50 000 networks on all seven
continents and outer space, with approximately 29 000
networks in the United States.
Such was the weight of the NSFNET program's ecumenism
and funding ($200 million from 1986 to 1995) — and the
quality of the protocols themselves — that by 1990 when the
ARPANET itself was finally decommissioned10, TCP/IP had
supplanted or marginalised most other wide-area computer
network protocols worldwide and IP was well on its way to
becoming the bearer service for the Global Information
Infrastructure.
Commercialisation of the Internet involved not only the
development of competitive, private network services, but also
the development of commercial products implementing the
Internet technology. In the early 1980s, dozens of vendors
were incorporating TCP/IP into their products because they
saw buyers for that approach to networking. Unfortunately they
lacked both real information about how the technology was
supposed to work and how the customers planned on using
this approach to networking. Many saw it as a nuisance add-on
that had to be glued onto their own proprietary networking
solutions: SNA, DECNet, Netware and NetBios. The DoD had
mandated the use of TCP/IP in many of its purchases, but
gave little help to the vendors regarding how to build useful
TCP/IP products.
In 1985, recognising this lack of information availability and
appropriate training, Dan Lynch in cooperation with the IAB
arranged to hold a three day workshop for all vendors to come
learn about how TCP/IP worked and what it still could not do
well. The speakers came mostly from the DARPA research
community who had both developed these protocols and used
them in day-to-day work. About 250 vendor personnel came to
listen to 50 inventors and experimenters. The results were
surprises on both sides: the vendors were amazed to find that
the inventors were so open about the way things worked (and
what still did not work) and the inventors were pleased to listen
to new problems they had not considered, but were being
discovered by the vendors in the field. Thus a two-way
discussion was formed that has lasted for over a decade.
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After two years of conferences, tutorials, design meetings and
workshops, a special event was organised that invited those
vendors whose products ran TCP/IP well enough to come
together in one room for three days to show off how well they
all worked together and also ran over the Internet. In
September of 1988 the first Interop trade show was born.
50 companies made the cut. 5 000 engineers from potential
customer organisations came to see if it all did work as was
promised. It did. Why? Because the vendors worked extremely
hard to ensure that everyone's products interoperated with all
of the other products — even with those of their competitors.
The Interop trade show has grown immensely since then and
today it is held in seven locations around the world each year
to an audience of over 250 000 people who come to learn
which products work with each other in a seamless manner,
learn about the latest products and discuss the latest
technology.
In parallel with the commercialisation efforts that were
highlighted by the Interop activities, the vendors began to
attend the IETF meetings that were held three or four times a
year to discuss new ideas for extensions of the TCP/IP
protocol suite. Starting with a few hundred attendees mostly
from academia and paid for by the government, these
meetings now often exceed a thousand attendees, mostly from
the vendor community and paid for by the attendees
themselves. This self-selected group evolves the TCP/IP suite
in a mutually cooperative manner. The reason it is so useful is
that it is composed of all stakeholders: researchers, end users
and vendors.
Network management provides an example of the interplay
between the research and commercial communities. In the
beginning of the Internet, the emphasis was on defining and
implementing protocols that achieved interoperation.
As the network grew larger, it became clear that the sometime
ad hoc procedures used to manage the network would not
scale. Manual configuration of tables was replaced by
distributed automated algorithms and better tools were devised
to isolate faults. In 1987 it became clear that a protocol was
needed that would permit the elements of the network, such as
the routers, to be remotely managed in a uniform way.
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Several protocols for this purpose were proposed, including
Simple Network Management Protocol or SNMP (designed, as
its name would suggest, for simplicity, and derived from an
earlier proposal called SGMP), HEMS (a more complex design
from the research community) and CMIP (from the OSI
community). A series of meetings led to the decisions that
HEMS would be withdrawn as a candidate for standardisation,
in order to help resolve the contention, but that work on both
SNMP and CMIP would go forward, with the idea that the
SNMP could be a more near-term solution and CMIP a longerterm approach. The market could choose the one it found
more suitable. SNMP is now used almost universally for
network-based management.
In the last few years, we have seen a new phase of
commercialisation. Originally, commercial efforts mainly
comprised vendors providing the basic networking products
and service providers offering the connectivity and basic
Internet services. The Internet has now become almost a
"commodity" service and much of the latest attention has been
on the use of this global information infrastructure for support
of other commercial services. This has been tremendously
accelerated by the widespread and rapid adoption of browsers
and the World Wide Web technology, allowing users easy
access to information linked throughout the globe. Products
are available to facilitate the provisioning of that information
and many of the latest developments in technology have been
aimed at providing increasingly sophisticated information
services on top of the basic Internet data communications.
On October 24, 1995, the FNC unanimously passed a
resolution defining the term Internet. This definition was
developed in consultation with members of the Internet and
intellectual property rights communities. Resolution: The
Federal Networking Council (FNC) agrees that the following
language reflects our definition of the term "Internet". "Internet"
refers to the global information system that — (i) is logically
linked together by a globally unique address space based on
the Internet Protocol (IP) or its subsequent extensions/ followons; (ii) is able to support communications using the
Transmission Control Protocol/ Internet Protocol (TCP/IP) suite
or its subsequent extensions/ follow-ons and/ or other IPcompatible protocols; and (iii) provides, uses or makes
accessible, either publicly or privately, high level services
layered on the communications and related infrastructure
described herein.
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The Internet has changed much in the two decades since it
came into existence. It was conceived in the era of timesharing, but has survived into the era of personal computers,
client-server, peer-to-peer computing and the network
computer. It was designed before LANs existed, but has
accommodated that new network technology, as well as the
more recent ATM and frame switched services. It was
envisioned as supporting a range of functions from file sharing
and remote login to resource sharing and collaboration and
has spawned electronic mail and more recently the World
Wide Web. But most important, it started as the creation of a
small band of dedicated researchers and has grown to be a
commercial success with billions of dollars of annual
investment.
One should not conclude that the Internet has now finished
changing. The Internet, although a network in name and
geography, is a creature of the computer, not the traditional
network of the telephone or television industry. It will, indeed it
must, continue to change and evolve at the speed of the
computer industry if it is to remain relevant. It is now changing
to provide new services such as real time transport, in order to
support, for example, audio and video streams.
The availability of pervasive networking (i.e., the Internet)
along with powerful affordable computing and communications
in portable form (i.e., laptop computers, two-way pagers,
PDAs, cellular phones), is making possible a new paradigm of
nomadic computing and communications. This evolution will
bring us new applications — Internet telephone and, slightly
further out, Internet television. It is evolving to permit more
sophisticated forms of pricing and cost recovery, a perhaps
painful requirement in this commercial world. It is changing to
accommodate yet another generation of underlying network
technologies with different characteristics and requirements,
e.g. broadband residential access and satellites. New modes
of access and new forms of service will spawn new
applications, which in turn will drive further evolution of the net
itself.
The most pressing question for the future of the Internet is not
how the technology will change, but how the process of
change and evolution itself will be managed. As this paper
describes, the architecture of the Internet has always been
driven by a core group of designers, but the form of that group
has changed as the number of interested parties has grown.
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With the success of the Internet has come a proliferation
of stakeholders — stakeholders now with an economic as
well as an intellectual investment in the network. We now
see, in the debates over control of the domain name space
and the form of the next generation IP addresses, a struggle to
find the next social structure that will guide the Internet in the
future. The form of that structure will be harder to find, given
the large number of concerned stakeholders. At the same time,
the industry struggles to find the economic rationale for the
large investment needed for the future growth, for example to
upgrade residential access to a more suitable technology. If
the Internet stumbles, it will not be because we lack for
technology, vision or motivation. It will be because we cannot
set a direction and march collectively into the future.
Timeline
3
Advantages of the Internet
Internet covers almost every aspect of life, one can think of.
Here, we will discuss some of the advantages of Internet:
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Internet allows us to communicate with the people sitting
at remote locations. There are various apps available on
the web that uses Internet as a medium for
communication. One can find various social networking
sites such as:
o
Facebook;
o
Twitter;
o
Yahoo;
o
Google+;
o
Flickr;
o
Orkut.
One can surf for any kind of information over the
Internet. Information regarding various topics such as
Technology, Health & Science, Social Studies,
Geographical Information, Information Technology,
Products, etc. can be surfed with help of a search
engine;
Apart from communication and source of information,
the Internet also serves a medium for entertainment.
Following are the various modes for entertainment over
Internet:
o
Online Television;
o
Online Games;
o
Songs;
o
Videos;
o
Social Networking Apps.
Internet allows us to use many services like:
o
Internet Banking;
o
Matrimonial Services;
o
Online Shopping;
o
Online Ticket Booking;
o
Online Bill Payment;
o
Data Sharing;
o
Email.
Internet provides concept of electronic commerce that
allows business deals to be conducted on electronic
systems.
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Disadvantages of the Internet
However, Internet has proved to be a powerful source of
information in almost every field, yet there exists many
disadvantages discussed below:


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
There are always chances to loose personal information
such as name, address and credit card number.
Therefore, one should be very careful while sharing
such information. One should use credit cards only
through authenticated sites;
Another disadvantage is the Spamming. Spamming
corresponds to the unwanted emails in bulk. These
emails serve no purpose and lead to obstruction of
entire system;
Viruses can easily be spread to the computers
connected to Internet. Such virus attacks may cause
your system to crash or your important data may get
deleted;
Also a biggest threat on the Internet is pornography.
There are many pornographic sites that can be found,
letting your children to use Internet which indirectly
affects the children healthy mental life;
There are various websites that do not provide the
authenticated information. This leads to misconception
among many people.
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The World Wide Web (WWW)
Overview of the World Wide Web
WWW stands for World Wide Web. A technical definition of the
World Wide Web is: all the resources and users on the Internet
that are using the Hypertext Transfer Protocol (HTTP). A
broader definition comes from the organisation that Web
inventor Tim Berners-Lee helped found, the World Wide Web
Consortium (W3C). The World Wide Web is the universe of
network-accessible information, an embodiment of human
knowledge.
In simple terms, the World Wide Web is a way of exchanging
information between computers on the Internet, tying them
together into a vast collection of interactive multimedia
resources.
Internet and Web is not the same thing: web uses Internet to
pass over the information.
5.2
Evolution of the WWW
The World Wide Web was created by Timothy Berners Lee in
1989 at CERN in Geneva. The World Wide Web came into
existence as a proposal by him, to allow researchers to work
together effectively and efficiently at CERN. Eventually it
became the World Wide Web. The following diagram briefly
defines evolution of the World Wide Web:
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WWW Architecture
WWW architecture is divided into several layers as shown in
the following diagram:
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Identifiers and Character Set
Uniform Resource Identifier (URI) is used to uniquely identify
resources on the web and UNICODE makes it possible to
build web pages that can be read and write in human
languages.
5.3.2
Syntax
XML (Extensible Mark-up Language) helps to define common
syntax in semantic web.
5.3.3
Data Interchange
Resource Description Framework (RDF) helps in defining
core representation of data for web. RDF represents data
about resource in graph form.
5.3.4
Taxonomies
RDF Schema (RDFS) allows more standardised description of
taxonomies and other ontological constructs.
5.3.5
Ontologies
Web Ontology Language (OWL) offers more constructs over
RDFS. It comes in following three versions:

OWL Lite for taxonomies and simple constraints;

OWL DL for full description logic support;

OWL for more syntactic freedom of RDF.
5.3.6
Rules
RIF and SWRL offers rules beyond the constructs that are
available from RDFs and OWL. Simple Protocol and RDF
Query Language (SPARQL) is SQL like language used for
querying RDF data and OWL Ontologies.
5.3.7
Proof
All semantic and rules that are executed at layers below Proof
and their result will be used to prove deductions.
5.3.8
Cryptography
Cryptography includes concepts such as digital signature for
verification of the origin of sources is used.
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User Interface and Applications
On the top of layer User interface and Applications a layer is
built for user interaction.
5.3.10 WWW Operation
WWW works on client-server approach. Following steps
explains how the web works:
1.
User
enters
the
URL
(say,
http://www.tutorialspoint.com) of the web page in the
address bar of web browser.
2.
Then browser requests the Domain Name Server for the
IP address corresponding to www.tutorialspoint.com.
3.
After receiving the IP address, the browser sends the
request for the web page to the web server using HTTP
protocol which specifies the way the browser and web
server communicates.
4.
Then the web server receives a request using HTTP
protocol and checks its search for the requested web
page. If found, it returns it back to the web browser and
closes the HTTP connection.
5.
Now the web browser receives the web page, it
interprets it and displays the contents of web page in
web browser’s window.
5.3.11 Future
There had been a rapid development in field of web. It has its
impact in almost every area such as education, research,
technology, commerce, marketing, etc. So the future of web is
almost unpredictable.
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5.3.12 User Interface
Work on higher quality presentation of 3D information is under
development. The W3 Consortium is also looking forward to
enhance the web to fulfil requirements of global communities
which would include all regional languages and writing
systems.
5.3.13 Technology
Work on privacy and security is under way. This would include
hiding information, accounting, access control, integrity and
risk management.
5.3.14 Architecture
There has been huge growth in field of web which may lead to
an overload of the Internet and degrade its performance.
Hence better protocols are required to be developed.
6
6.1
Web Pages
Overview
Web page is a document available on World Wide Web. Web
Pages are stored on web server and can be viewed using a
web browser. A web page can contain huge information
including text, graphics, audio, video and hyperlinks. These
hyperlinks are the link to other web pages.
Collections of linked web pages on a web server are known as
a website. There is unique Uniform Resource Locator (URL) is
associated with each web page.
6.2
Static Web Page
Static web pages are also known as flat or stationary web
pages. They are loaded on the client’s browser exactly as they
are stored on the web server. Such web pages contain only
static information. User can only read the information, but
cannot do any modification or interact with the information.
Static web pages are created using only HTML. Static web
pages are only used when the information is no more required
to be modified.
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Dynamic Web Page
Dynamic web pages show different information at different
points of time. It is possible to change a portion of a web page
without loading the entire web page. It has been made
possible using Ajax technology.
6.3.1
Server-Side Dynamic Web Page
It is created by using server-side scripting. There are serverside scripting parameters that determine how to assemble a
new web page, which also includes setting up of more clientside processing.
6.3.2
Client-Side Dynamic Web Page
It is processed using client side scripting, such as JavaScript,
and then passed in to Document Object Model (DOM).
6.3.3
Scripting Languages
Scripting languages are like programming languages that allow
us to write programs in the form of script. These scripts are
interpreted not compiled and executed line by line. Scripting
language is used to create dynamic web pages.
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Client-side Scripting
Client-side scripting refers to the programs that are executed
on client-side. Client-side scripts contain the instruction for the
browser to be executed in response to certain user’s action.
Client-side scripting programs can be embedded into HTML
files or also can be kept as separate files.
Following table describes commonly used Client-Side scripting
languages:
Scripting Language Description
1. JavaScript
It is a prototype-based scripting language. It inherits its
naming conventions from java. All java script files are
stored in file having .js extension.
2. ActionScript
It is an object-oriented programming language used for the
development of websites and software targeting Adobe
flash player.
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Scripting Language Description
3. Dart
It is an open-source web programming language developed
by Google. It relies on source-to-source compiler to
JavaScript.
4. VBScript
It is an open-source web programming language developed
by Microsoft. It is superset of JavaScript and adds optional
static typing class-based object-oriented programming.
6.3.5
Server-side Scripting
Sever-side scripting acts as an interface for the client and also
limits the user’s access the resources on web server. It can
also collect the user’s characteristics in order to customise a
response.
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Following table describes
scripting languages:
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commonly
used
Server-Side
Scripting Language Description
1. ASP
Active Server Pages (ASP) is server-side script engine to
create dynamic web pages. It supports Component Object
Model (COM), which enables ASP web sites to access
functionality of libraries such as DLL.
2. ActiveVFP
It is similar to PHP and also used for creating dynamic web
pages. It uses native Visual FoxPro language and
database.
3. ASP.net
It is used to develop dynamic websites, web applications
and web services.
4. Java
Java Server Pages are used for creating dynamic web
applications. The Java code is compiled into byte code and
run by Java Virtual Machine (JVM).
5. Python
It supports multiple programming paradigms such as
object-oriented and functional programming. It can also be
used as non-scripting language using third party tools such
as Py2exe or Pyinstaller.
6. WebDNA
It is also a server-side scripting language with an
embedded database system.
7
7.1
Web Browser
Overview
Web Browser is an application software that allows us to view
and explore information on the web. Users can request any
web page by just entering a URL into address bar. Web
browsers can show text, audio, video, animation and more. It is
the responsibility of a web browser to interpret text and
commands contained in the web page.
Earlier the web browsers were text-based, while nowadays
graphical-based or voice-based web browsers are also
available.
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Following are the most common web browser available today:
Browser
Vendor
Internet Explorer
Microsoft
Google Chrome
Google
Mozilla Firefox
Mozilla
Netscape Navigator
Netscape Communications Corp.
Opera
Opera Software
Safari
Apple
Sea Monkey
Mozilla Foundation
K-meleon
K-meleon
7.1.1
Architecture
There are a lot of web browsers available in the market. All of
them interpret and display information on the screen; however,
their capabilities and structure vary depending upon
implementation. But the most basic component that all web
browsers must exhibit are listed below:

Controller/ Dispatcher;

Interpreter;

Client Programs.
Controller works as a control unit in CPU. It takes input from
the keyboard or mouse, interprets it and makes other services
work on the basis of input it receives.
Interpreter receives the information from the controller and
executes the instruction line by line. Some interpreters are
mandatory while some are optional. For example, HTML
interpreter program is mandatory and java interpreter is
optional.
Client Program describes the specific protocol that will be used
to access a particular service. Following are the client
programs that are commonly used:

HTTP;

SMTP;

FTP;

NNTP;

POP.
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Starting Internet Explorer
Internet explorer is a web browser developed by Microsoft. It is
installed by default with the windows operating system
however, it can be downloaded and be upgraded.
To start Internet explorer, follow the following steps:

Go to Start button and click Internet Explorer;
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The Internet Explorer window will appear as shown in
the following diagram:
Accessing Web Page
Accessing a web page is very simple. Just enter the URL in
the address bar as shown the following diagram:
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Navigation
A web page may contain hyperlinks. When we click on these
links another web page is opened. These hyperlinks can be in
form of text or image. When we take the mouse over a
hyperlink, the pointer changes its shape to hand.
Key Points:

In case you have accessed many web pages and are
willing to see the previous webpage then just click back
button;

You can open a new web page in the same tab or
different tab or in a new window.
7.1.5
Saving Webpage
You can save web page to use in future. In order to save a
webpage, follow the steps given below:

Click File > Save As. Save Webpage dialog box
appears;

Choose the location where you want to save your
webpage from save in: list box. Then choose the folder
where you want to save the webpage;

Specify the file name in the File name box;

Select the type from Save as type list box:
o
Webpage, complete;
o
Web Archive;
o
Webpage HTML only;
o
Text File.
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From the encoding list box, choose the character set
which will be used with your webpage. By default,
Western European is selected;
Click save button and the webpage is saved.
Saving Web Elements
Web elements are the pictures, links, etc. In order to save
these elements follow the steps given below:

Right click on the web page element you want to save.
Menu options will appear. These options may vary
depending on the element you want to save.
Save Picture As — This option lets you save the picture at
specific location with its name. When you click this option, a
dialog box is opened where you can specify its name and
location.
7.1.7
Favourites
The Favourites option helps to save addresses of the web
pages you visited often. Hence you need not to remember long
and complex address of websites you visit often. In order to
open any web page, you just need to double click on the web
page that you have marked from bookmarks list.
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Adding a Web Page to your Favourites
In order to add a website to your favourite list, follow the steps
given below:

Open the web page that you want to add to your
favourite;

Click on favourite menu and then click on the Add to
Favourites option. The add favourites dialog box
appears.

You can also click the Favourites button available in the
toolbar. Favourite’s panel will open in the left corner of
the Internet explorer window. Click the add button, the
Add Favourites dialog box will appear.

In Add Favourites dialog box, the Name: text box will
contains the name of the web page that you want to add
to favourites;
Click the Create in button, the Favourites folder will
appear. Move to the folder where you want to store the
favourites by clicking on the folder name;
Now click the OK button to save the favourites.


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Opening Favourites
In order to open favourites, follow the steps given below:

In the Favourite Panel, take the mouse over the site that
you want to open. Now click on the address to open that
site.

Favourite can also be opened from the Favourites menu
by selecting the appropriate one.
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Organising Favourites
Favourites can be organised by categorising web pages,
creating folders for each category and then storing web pages
into them. In order to organise favourites, follow the steps
given below:

Click Favourites menu > Organize Favourites. Organize
favourites dialog box will appears;

In order to organise the webpages, drag the individual
web page to the respective folder. Similarly, to delete a
favourite, click on delete button.
8
8.1
Search Engines
Overview
Search Engine refers to a huge database of Internet resources
such as web pages, newsgroups, programs, images, etc. It
helps to locate information on World Wide Web. Users can
search for any information by passing a query in the form of
keywords or phrase. It then searches for relevant information
in its database and return to the user.
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Search Engine Components
Generally there are three basic components of a search
engine as listed below:
1.
Web Crawler
2.
Database
3.
Search Interfaces
Web crawler
It is also known as spider or bots. It is a software component
that traverses the web to gather information.
Database
All the information on the web is stored in database. It consists
of huge web resources.
Search Interfaces
This component is an interface between user and the
database. It helps the user to search through the database.
8.1.2
Search Engine Working
Web crawler, database and the search interface are the major
components of a search engine that actually makes search
engine to work. Search engines make use of Boolean
expression and, or, not to restrict and widen the results of a
search.
Following are the steps that are performed by the search
engine:

The search engine looks for the keyword in the index for
predefined database instead of going directly to the web
to search for the keyword;

It then uses software to search for the information in the
database. This software component is known as web
crawler;

Once web crawler finds the pages, the search engine then
shows the relevant web pages as a result. These retrieved
web pages generally include title of page, size of text
portion, first several sentences, etc.
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These search criteria may vary from one search engine
to the other. The retrieved information is ranked
according to various factors such as frequency of
keywords, relevancy of information, links, etc.;
Users can click on any of the search results to open it.
Architecture
The search engine architecture comprises of the three basic
layers listed below:

Content collection and refinement;

Search core;

User and application interfaces.
8.2
Search Engine Processing
8.2.1
Indexing Process
Indexing process comprises of the following three tasks:

Text acquisition;

Text transformation;

Index creation.
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Text Acquisition
It identifies and stores documents for indexing.
8.2.3
Text Transformation
It transforms document into index terms or features.
8.2.4
Index Creation
It takes index terms created by text transformations and
creates data structures to support fast searching.
8.2.5
Query Process
Query process comprises of the following three tasks:

User interaction;

RANKING;

Evaluation.
User Interaction
It supports creation and refinement of user query and displays
the results.
RANKING
It uses query and indexes to create ranked list of documents.
Evaluation
It monitors and measures the effectiveness and efficiency. It is
done offline.
Examples
Following are the several search engines available today:
Search
Engine
Description
Google
It was originally called BackRub. It is the most
popular search engine globally.
Bing
It was launched in 2009 by Microsoft. It is the
latest web-based search engine that also
delivers Yahoo’s results.
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Description
Ask
It was launched in 1996 and was originally
known as Ask Jeeves. It includes support for
match, dictionary and conversation question.
AltaVista
It was launched by Digital Equipment
Corporation in 1995. Since 2003, it is powered
by Yahoo technology.
AOL.Search It is powered by Google.
LYCOS
It is top 5 Internet portal and 13th largest online
property according to Media Matrix.
Alexa
It is subsidiary of Amazon and used for providing
website traffic information.
9
9.1
Websites
Overview
Website is a location on web and is hosted on a web server. It
is a set of related web pages. It is accessed using an Internet
address known as Uniform Resource Locator.
9.2
Static Websites
Static websites are also known as flat or stationary websites.
They are loaded on the client’s browser exactly as they are
stored on the web server. Such websites contain only static
information. User can only read the information, but cannot do
any modification or interact with the information. Static
websites are created using only HTML. Static websites are
only used when the information is no more required to be
modified.
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Dynamic Websites
Dynamic websites show different information at different points
of time. It is possible to change a portion of a web page without
loading the entire web page. It has been made possible using
Ajax technology.
9.3.1
Server-side Dynamic Web Page
It is created by using server-side scripting. There are serverside scripting parameters that determine how to assemble a
new web page, which also includes setting up of more clientside processing.
9.3.2
Client-side Dynamic Web Page
It is processed using client-side scripting such as JavaScript
and then is passed in to Document Object Model (DOM).
9.4
Websites Types
9.4.1
Internet Forums
An Internet forum is message board where people can hold
conversations by posting messages.
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Key Points

A forum can contain several sub-forums;

Each of sub-forum may contain a number of topics;

Within a forum’s topic, each new discussion started is
called a thread;

This thread can be replied to by as many people as so
wish.
9.4.2
Blog
The term Blog is taken from web log. It is a kind of web site
that is updated regularly, with content about almost anything.
In other words, blog is a Content Management System (CMS),
an easy way of publishing articles on the Internet.
Blogging Terminologies

BLOG — A type of website used to publish content on
the Internet;

BLOGGER — A person who writes for a blog;

BLOGGING — Writing for blogs is referred as blogging;

BLOGOSPHERE — A term is used to refer all the blogs
on the web.
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What to Blog about
Following discussion will help you to figure out what to write
about and as well as what to name your blog:

Write what you know about. For example, if you have
good computer knowledge. You can write what you
know about the subject;

You can share your experience. You can also write what
you gained from that experience, what you learned;

Detail your personal research;

Share your memory of someone.
10 E-commerce
E-Commerce or Electronic Commerce is a methodology of
modern business which addresses the need of business
organisations, vendors and customers to reduce cost and
improve the quality of goods and services while increasing the
speed of delivery. E-commerce refers to paperless exchange
of business information using following ways:

Electronic Data Exchange (EDI);

Electronic Mail (email);

Electronic Bulletin Boards;

Electronic Fund Transfer (EFT);

Other Network-based technologies.
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10.1 Features
E-Commerce provides following features:
1.
Non-cash payment

E-Commerce enables use of credit cards, debit
cards, smart cards, electronic fund transfer via
bank's website and other modes of electronics
payment.
2.
24x7 service availability

E-commerce automates business of enterprises
and services provided by them to customers are
available anytime, anywhere. Here 24x7 refers to
24 hours of each seven days of a week.
3.
Advertising/ marketing

E-commerce increases the reach of advertising of
products and services of businesses. It helps in
better marketing management of products/
services.
4.
Improved sales

Using E-Commerce for orders means the products
can be generated anytime, anywhere without any
human intervention. By this way, dependencies to
buy a product reduce at large and sales increases.
5.
Support

E-Commerce provides various ways to provide
pre-sales and post-sales assistance to provide
better services to customers.
10.2 Portfolio
Online portfolio is collection of images, multimedia, emails,
blog entries and hyperlinks that are managed online. It can be
seen as a kind of learning record that provides actual evidence
of achievement.
10.3 Types
There are three types of online portfolio:

Developmental (e.g. working): Developmental
portfolio contains all the things that an individual has
done over a period of time;
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Reflective (e.g. learning): Reflective portfolio
contains personal reflection on the content;
Representational (e.g. showcase): Representational
online portfolio refers to learner’s achievement in a
particular work.
10.4 Website Security Consideration
Websites are always to prone to security risks. Cybercrime
impacts your business by hacking your website. Your website
is then used for hacking assaults that install malicious software
or malware on your visitor’s computer. Hackers may also steal
important customer data such as credit card information,
destroy your business and propagate illegal content to your
users.
10.4.1 Security Considerations

Updated Software
It is mandatory to keep your software updated. It plays
vital role in keeping your website secure.

SQL Injection
It is an attempt by the hackers to manipulate your
database. It is easy to insert rogue code into your query
that can be used to manipulate your database such as
change tables, get information or delete data.

Cross Site Scripting (XSS)
It allows the attackers to inject client-side script into web
pages. Therefore, while creating a form, it is good to
ensure that you check the data being submitted and
encode or strip out any HTML.

Error Messages
You need to be careful about how much information to
be given in the error messages. For example, if the user
fails to log in the error message should not let the user
know which field is incorrect: username or password.

Validation of Data
The validation should be performed on both server side
and client side.
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Passwords
It is good to enforce password requirements such as of
minimum of eight characters, including upper case, lower
case and special character. It will help to protect user’s
information in the long-run.

Upload files
The file uploaded by the user may contain a script that
when executed on the server opens up your website.

SSL
It is good practice to use SSL protocol while passing
personal information between website and web server or
database.
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10.5 Search Engine Optimization
10.5.1 What is SEO
Search Engine Optimization refers to set of activities that are
performed to increase the number of desirable visitors who
come to your site via search engine. These activities may
include the things you do to your site itself, such as making
changes to your text and HTML code, formatting text or
document to communicate directly to the search engine.
10.5.2 Types of SEO
SEO can be classified into two types: White Hat SEO
and Black Hat or Spamdexing
White Hat SEO
An SEO tactic, technique or method is considered as White
Hat if it follows the following:

If it conforms to the search engine's guidelines;

If it does not involve any deception;

It ensures that the content a search engine indexes and
subsequently ranks is the same content a user will see;

It ensures that a web page content should have been
created for the users and not just for the search engines;

It ensures the good quality of the web pages;

It ensures the useful content available on the web
pages.
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Always follow a White Hat SEO tactic and do not try to fool
your site visitors. Be honest and definitely you will get
something more.
Black Hat or Spamdexing
An SEO tactic, technique or method is considered as Black
Hat or Spamdexing if it follows the following:

Tries to improve rankings that are disapproved of by the
search engines and/ or involve deception;

Redirects users from a page that is built for search
engines to one that is more human friendly;

Redirects users to a page that was different from the
page the search engine ranked;

Serves one version of a page to search engine spiders/
bots and another version to human visitors. This is
called Cloaking SEO tactic;

Uses hidden or invisible text or with the page
background colour, using a tiny font size or hiding them
within the HTML code such as "no frame" sections;

Repeats keywords in the Meta tags and uses keywords
that are unrelated to the site's content. This is called
Meta tag stuffing;

Calculates placement of keywords within a page to raise
the keyword count, variety and density of the page. This
is called Keyword stuffing;

Creates low-quality web pages that contain very little
content, but are instead stuffed with very similar key
words and phrases. These pages are called Doorway or
Gateway Pages;

Mirror web sites by hosting multiple web sites all with
conceptually similar content, but using different URLs;

Creates a rogue copy of a popular web site which shows
contents similar to the original to a web crawler, but
redirects web surfers to unrelated or malicious web
sites. This is called Page hijacking.
10.5.3 Key Elements to Ethical SEO
Keyword research
It allows you to see which keywords users actually employ to
find products and services within your chosen market, instead
of making guesses at the keywords you believe are the most
popular.
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Content development
Content development involves:

Navigational flow and menu structure;

Site copy or articles;

Headings and sections.
Web development
Web development involves:
Text-based site development wherever possible;
Clean and logical site structure;
Proper mark-up of key page elements.



Link Building
Building links will make up about 60% of your work. There are
ways to automate this process by using shortcuts,
workarounds, and submission services. Internal linking is also
very important. Treat the way you link to your own content
same as you would link from an external site.
Webmaster Tools
Webmaster dashboard is provided by both Google and Bing
that gives insight into activity by the search engine on any site
that has been registered and verified via dashboard.
Dashboards offer a number of tools which allow us to
understand how the search engine sees your site. These are
the only way to identify crawling, indexing and the ranking
issue with your site.
10.6 SEO Do’s and Don’ts
10.6.1 DO's
There are various other tips which can help you to optimise
your web site for many Search Engines:

Create logs of pages and each page should, however,
contain a minimum of about 200 visible words of text to
maximise relevance with Google;

Create a Sitemap, Help, FAQ, About Us, Link to Us,
Copyright, Disclaimer and Privacy Policy pages on
mandatory basis;

Create a home page link to each and every web page
and provide easy navigation through all the pages;
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Pay attention to your dynamic page URLs. Google can
crawl and index dynamic pages as long as you do not
have more than two parameters in the URL;
Check your complete site for broken links. Broken links
will reduce your other pages rank as well.
10.6.2 Don’ts
Here is the list of Don’ts that one should keep in mind all the
times:

Do not keep hidden text on your web pages;

Do not create alt image spamming by putting wrong
keywords;

Do not use Meta tags stuffing;

Do not use frames and flash on your site;

Do not exchange your links with black listed sites;

Do not try to fool your site visitors by using miss spelled
keywords;

Do not send spam emails to thousands of email IDs;

Do not use too many graphics on your site;

Do not create too many doorway pages;

Do not try to create duplicate content of pages;

Do not submit your website many times in a single
search engine;

Do not use sub-directory depth more than one to two;

Do not create too many dynamic pages. Try to convert
them into static pages;

Do not bloat your pages with code;

Do not nest your pages.
10.7 Website Monetisation
Website monetisation refers to making money from the
website. It is done by converting existing traffic to a particular
website into revenue.
10.7.1 Methods of Monetisation
Display Advertising
Display advertising refers to the banners and text ads. This
method is good for the websites that have significant traffic,
valuable audience, relevant and active advertisers.
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Affiliate Marketing
Affiliate marketing refers to steering the visitors to products
and services of a third party merchant. It is good for the
websites that are product-centric and have easy integration
into content.
Lead generation
Lead generation refers to capturing the customer information
and selling it to a third party.
Email rental
Email rentals refer to renting out your email lists to third
parties. In this you will send an email on their behalf to your
distribution list.
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Chapter 2: Reference Models
1
1.1
Introduction to reference models
Overview of Reference Model
Reference Model offers a means of standardisation which is
acceptable worldwide. Since people using the computer
network are located over a wide physical range and their
network devices might have heterogeneous architecture. In
order to provide communication among heterogeneous
devices, we need a standardised model, i.e. a reference
model, which would provide us a way how these devices can
communicate regardless their architecture.
We have two reference models such as OSI model and
TCP/IP reference model, however, the OSI model is a
hypothetical one, but the TCP/IP is absolutely practical model.
2
Open System Interface (OSI) Model
OSI is acronym of Open System Interface. This model is
developed by the International organization of Standardization
(ISO) and, therefore, also referred as ISO-OSI Model.
The OSI model consists of seven layers as shown in the
following diagram. Each layer has a specific function; however
each layer provides services to the layer above.
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Activities and Functions of the Layers of
the OSI Model
2.1.1
Physical Layer
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The Physical layer is responsible for the following activities:

Activating, maintaining and deactivating the physical
connection;

Defining voltages and data rates needed for
transmission;

Converting digital bits into electrical signal;

Deciding whether the connection is simplex, half duplex
or full duplex.
2.1.2
Data Link Layer
The data link layer performs the following functions:

Performs synchronisation and error control for the
information which is to be transmitted over the physical
link;

Enables error detection and adds error detection bits to
the data which are to be transmitted.
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Network Layer
Following are the functions of Network Layer:

To route the signals through various channels to the
other end;

To act as the network controller by deciding which route
data should take;

To divide the outgoing messages into packets and to
assemble incoming packets into messages for higher
levels.
2.1.4
Transport Layer
The Transport layer performs the following functions:

It decides if the data transmission should take place on
parallel paths or single path;

It performs multiplexing, splitting on the data;

It breaks the data groups into smaller units so that they
are handled more efficiently by the network layer.
The Transport Layer guarantees transmission of data from one
end to other end.
2.1.5
Session Layer
The Session layer performs the following functions:

Manages
the
messages
and
synchronises
conversations between two different applications;

It controls logging on and off, user identification, billing
and session management.
2.1.6
Presentation Layer
The Presentation layer performs the following functions:

This layer makes it sure that the information is delivered
in such a form that the receiving system will understand
and use it.
2.1.7
Application Layer
The Application layer performs the following functions:

It provides different services such as manipulation of
information in several ways, retransferring the files of
information, distributing the results, etc.;

The functions such as login or password checking are
also performed by the application layer.
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TCP/IP Model
TCP/IP model is practical model and is used in the Internet.
TCP/IP is acronym of Transmission Control Protocol and
Internet Protocol. The TCP/IP model combines the two layers
(Physical and Data link layer) into one layer, i.e. Host-toNetwork layer. The following diagram shows the various
layers of TCP/IP model:
3.1
Activities and Functions of the Layers of
the Internet Model
3.1.1
Application Layer
This layer is same as that of the OSI model and performs the
following functions:

It provides different services such as manipulation of
information in several ways, retransferring the files of
information, distributing the results, etc.;

The functions such as login or password checking are
also performed by the application layer.
Protocols used: TELNET, FTP, SMTP, DN, HTTP, NNTP are
the protocols employed in this layer.
3.1.2
Transport Layer
It does the same functions as that of transport layer in OSI
model. Here are the key points regarding transport layer:

It uses TCP and UDP protocol for end to end
transmission;

TCP is reliable and connection-oriented protocol;
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TCP also handles flow control;
The UDP is not reliable and a connection-less protocol
also does not perform flow control.
Protocols used: TCP/IP and UDP protocols are employed in
this layer.
3.1.3
Internet Layer
The function of this layer is to allow the host to insert packets
into a network and then make them travel independently to the
destination. However, the order of receiving the packet can be
different from the sequence they were sent.
Protocols used: Internet Protocol (IP) is employed in Internet
layer.
3.1.4
Host-to-Network Layer
This is the lowest layer in TCP/IP model. The host has to
connect to a network using some protocol, so that it can send
IP packets over it. This protocol varies from host to host and
network to network.
Protocols used: ARPANET, SATNET, LAN, packet radio are
the protocols which are used in this layer.
4
4.1
Internet Protocols
Transmission Control Protocol (TCP)
TCP is a connection-oriented protocol and offers end-to-end
packet delivery. It acts as back bone for connection. It exhibits
the following key features:

Transmission Control Protocol (TCP) corresponds to the
Transport Layer of OSI Model;

TCP is a reliable and connection oriented protocol;

TCP offers:
o
Stream Data Transfer;
o
Reliability;
o
Efficient Flow Control;
o
Full-duplex operation;
o
Multiplexing.

TCP offers connection-oriented end-to-end packet
delivery;
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4.2
TCP ensures reliability by sequencing bytes with
forwarding acknowledgement number that indicates
the destination the next byte the source expects
receive;
It retransmits the bytes not acknowledged with
specified time period.
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a
to
to
in
TCP Services
TCP offers following services to the processes at the
application layer:

Stream Delivery Service;

Sending and Receiving Buffers;

Bytes and Segments;

Full Duplex Service;

Connection Oriented Service;

Reliable Service.
4.2.1
Stream Deliver Service
TCP protocol is stream oriented, because it allows the sending
process to send data as a stream of bytes and the receiving
process to obtain data as a stream of bytes.
4.2.2
Sending and Receiving Buffers
It may not be possible for the sending and receiving process to
produce and obtain data at same speed, therefore, TCP needs
buffers for storage at sending and receiving ends.
4.2.3
Bytes and Segments
The Transmission Control Protocol (TCP), at transport layer
groups the bytes into a packet. This packet is called a
segment. Before transmission of these packets, these
segments are encapsulated into an IP datagram.
4.2.4
Full Duplex Service
Transmitting the data in duplex mode means flow of data in
both the directions at the same time.
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Connection-oriented Service
TCP offers connection oriented service in the following
manner:
1.
TCP of process-1 informs TCP of process-2 and gets its
approval.
2.
TCP of process-1 and TCP of process-2 and exchange
data in both the two directions.
3.
After completing the data exchange, when buffers on
both sides are empty, the two TCP’s destroy their
buffers.
4.2.6
Reliable Service
For sake of
mechanism.
4.3
reliability,
TCP
uses
acknowledgement
Internet Protocol (IP)
Internet Protocol is a connectionless and unreliable protocol. It
ensures no guarantee of successfully transmission of data. In
order to make it reliable, it must be paired with reliable protocol
such as TCP at the transport layer.
Internet protocol transmits the data in form of a datagram as
shown in the following diagram:
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Points to remember:

The length of datagram is variable;

The Datagram is divided into two parts: header and
data;

The length of header is 20 to 60 bytes;

The header contains information for routing and delivery
of the packet.
4.4
User Datagram Protocol (UDP)
Like IP, UDP is a connectionless and unreliable protocol. It
does not require making a connection with the host to
exchange data. Since UDP is an unreliable protocol, there is
no mechanism for ensuring that data sent is received.
UDP transmits the data in form of a datagram. The UDP
datagram consists of five parts as shown in the following
diagram:
Points to remember:

UDP is used by the application that typically transmit
small amount of data at one time;

UDP provides protocol port used, i.e. UDP messages
contain both source and destination port number, that
makes it possible for UDP software at the destination to
deliver the message to correct application program.
4.5
File Transfer Protocol (FTP)
FTP is used to copy files from one host to another. FTP offers
the mechanism for the same in following manner:

FTP creates two processes such as Control Process
and Data Transfer Process at both ends, i.e. at client as
well as at server;

FTP establishes two different connections: one is for
data transfer and other is for control information;
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
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Control connection is made between control processes
while Data Connection is made between <="" b=""
style="box-sizing: border-box;">;
FTP uses port 21 for the control connection and Port 20
for the data connection.
Trivial File Transfer Protocol (TFTP)
Trivial File Transfer Protocol is also used to transfer the files,
but it transfers the files without authentication. Unlike FTP,
TFTP does not separate control and data information. Since
there is no authentication exists, TFTP lacks in security
features, therefore, it is not recommended to use TFTP.
Key points:

TFTP makes use of UDP for data transport. Each TFTP
message is carried in separate UDP datagram;

The first two bytes of a TFTP message specify the type
of message;

The TFTP session is initiated when a TFTP client sends
a request to upload or download a file;

The request is sent from an ephemeral UDP port to the
UDP port 69 of an TFTP server.
4.7
Difference between FTP and TFTP
S.N.
Parameter
FTP
TFTP
1
Operation
Transferring Files
Transferring Files
2
Authentication
Yes
No
3
Protocol
TCP
UDP
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S.N.
Parameter
FTP
TFTP
4
Ports
21 — Control, 20 — Data
Port 3 214, 69, 4 012
5
Control and Data
Separated
Separated
6
Data Transfer
Reliable
Unreliable
4.8
Telnet
Telnet is a protocol used to log in to a remote computer on the
Internet. There are a number of Telnet clients having user
friendly user interface. The following diagram shows a person
is logged in to computer A, and from there, he is remotely
logged into computer B.
4.9
Hyper Text Transfer Protocol (HTTP)
HTTP is a communication protocol. It defines mechanism for
communication between browser and the web server. It is also
called request and response protocol because the
communication between browser and server takes place in
request and response pairs.
4.9.1
HTTP Request
HTTP request comprises of lines which contains:

Request line;

Header Fields;

Message body.
Key Points

The first line, i.e. the Request line specifies the request
method, i.e. Get or Post;

The second line specifies the header which indicates the
domain name of the server from where index.htm is
retrieved.
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HTTP Response
Like HTTP request, HTTP response also has certain structure.
HTTP response contains:

Status line;

Headers;

Message body.
Internet Services
5
Internet Services allows us to access huge amounts of
information such as text, graphics, sound and software over
the Internet. Following diagram shows the four different
categories of Internet Services:
5.1
Communication Services
There are various Communication Services available that offer
exchange of information with individuals or groups. The
following table gives a brief introduction to these services:
Service Description
1
Electronic Mail (email)
Used to send electronic messages over the Internet.
2
Telnet
Used to log on to a remote computer that is attached to
Internet.
3
Newsgroup
Offers a forum for people to discuss topics of common
interests.
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Service Description
4
Internet Relay Chat (IRC)
Allows the people from all over the world to communicate
in real time.
5
Mailing Lists
Used to organise group of Internet users to share common
information through email.
6
Internet Telephony (VoIP)
Allows the Internet users to talk across Internet to any PC
equipped to receive the call.
7
Instant Messaging
Offers real time chat between individuals and group of
people. E.g. Yahoo messenger, MSN messenger.
5.2
Information Retrieval Services
There exist several Information retrieval services offering easy
access to information present on the Internet. The following
table gives a brief introduction to these services:
Service Description
1
File Transfer Protocol (FTP)
Enable the users to transfer files.
2
Archie
It is an updated database of public FTP sites and their
content. It helps to search a file by its name.
3
Gopher
Used to search, retrieve and display documents on
remote sites.
4
Very Easy Rodent Oriented Netwide Index to
Computer Achieved (VERONICA)
VERONICA is gopher-based resource. It allows access to
the information resource stored on gopher’s servers.
5.3
Web Services
Web services allow exchange of information between
applications on the web. Using web services, applications can
easily interact with each other. The web services are offered
using concept of Utility Computing.
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World Wide Web (WWW)
WWW is also known as W3. It offers a way to access
documents spread over the several servers over the Internet.
These documents may contain texts, graphics, audio, video
and hyperlinks. The hyperlinks allow the users to navigate
between the documents.
5.5
Video Conferencing
Video conferencing or Video teleconferencing is a method of
communicating by two-way video and audio transmission with
help of telecommunication technologies.
5.5.1
Modes of Video Conferencing
Point-To-Point
This mode of conferencing connects two locations only.
Multi-Point
This mode of conferencing connects more than two locations
through Multi-point Control Unit (MCU).
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Internet Connectivity
Here in this section, we will discuss how to connect to the
Internet, i.e. Internet service providers, software and hardware
requirements, configuring Internet connection, etc.
6.1
Internet Service Providers (ISP)
Internet Service Provider (ISP) is a company offering access to
Internet. They offer various services:

Internet Access;

Domain name registration;

Dial-up access;

Leased line access.
6.1.1
ISP Types
ISPs can broadly be classified into six categories as shown in
the following diagram:





Access Providers — They provide access to the Internet
through telephone lines, cable, Wi-Fi or fiber optics;
Mailbox Provider — Such providers offer mailbox hosting
services;
Hosting ISPS — Hosting ISPs offer email and other web
hosting services such as virtual machines, clouds, etc.;
Virtual ISPS — Such ISPs offer Internet access via other
ISP services;
Free ISPS —Free ISPs do not charge for Internet
services.
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Connection Types
Several ways exist to connect to the Internet. Following are
these connection types available:
1.
Dial-up Connection
2.
ISDN
3.
DSL
4.
Cable TV Internet connections
5.
Satellite Internet connections
6.
Wireless Internet Connections
7.1
Dial-up Connection
Dial-up connection uses telephone line to connect a PC to the
Internet. It requires a modem to setup dial-up connection. This
modem works as an interface between the PC and the
telephone line. There is also a communication program that
instructs the modem to make a call to specific number
provided by an ISP.
Dial-up connection uses either of the following protocols:
1.
Serial Line Internet Protocol (SLIP)
2.
Point to Point Protocol (PPP)
The following diagram shows the accessing Internet using
modem:
7.2
ISDN
ISDN is acronym of Integrated Services Digital Network. It
establishes the connection using the phone lines which carry
digital signals instead of analogue signals. There are two
techniques to deliver ISDN services:
1.
Basic Rate Interface (BRI)
2.
Primary Rate Interface (PRI)
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Key points:

The BRI ISDN consists of three distinct channels on a
single ISDN line: t1o 64kbps B (Bearer) channel and
one 16kbps D (Delta or Data) channels;

The PRI ISDN consists of 23 B channels and one D
channel with both having an operating capacity of
64kbps individually making a total transmission rate of
1.54Mbps.
The following diagram shows accessing Internet using ISDN
connection:
7.3
DSL
DSL is acronym of Digital Subscriber Line. It is a form of
broadband connection as it provides connection over ordinary
telephone lines.
Following are the several versions of DSL technique available
today:
1.
Asymmetric DSL (ADSL)
2.
Symmetric DSL (SDSL)
3.
High bit-rate DSL (HDSL)
4.
Rate adaptive DSL (RDSL)
5.
Very high bit-rate DSL (VDSL)
6.
ISDN DSL (IDSL)
All of the above mentioned technologies differ in their upload
and download speed, bit transfer rate and level of service.
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The following diagram shows that how we can connect to
Internet using DSL technology:
7.4
Cable TV Internet Connection
Cable TV Internet connection is provided through Cable TV
lines. It uses coaxial cable which is capable of transferring data
at much higher speed than common telephone line.
Key Points:

A cable modem is used to access this service, provided
by the cable operator;

The Cable modem comprises of two connections: one
for Internet service and other for Cable TV signals;

Since Cable TV Internet connections share a set amount
of bandwidth with a group of customers, therefore, data
transfer rate also depends on number of customers
using the Internet at the same time.
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The following diagram shows that how Internet is accessed
using Cable TV connection:
7.5
Satellite Internet Connection
Satellite Internet connection offers high speed connection to
the Internet. There are two types of satellite Internet
connection: one way connection or two way connection. In one
way connection, we can only download data, but if we want to
upload, we need a dialup access through ISP over telephone
line. In two way connection, we can download and upload the
data by the satellite. It does not require any dialup connection.
The following diagram shows how Internet is accessed using
satellite Internet connection:
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Wireless Internet Connection
Wireless Internet Connection makes use of radio frequency
bands to connect to the Internet and offers a very high speed.
The wireless Internet connection can be obtained by either WiFi or Bluetooth.
Key Points:

Wi-Fi wireless technology is based on IEEE 802.11
standards which allow the electronic device to connect
to the Internet;

Bluetooth wireless technology makes use of shortwavelength radio waves and helps to create personal
area network (PAN).
7.7
Features of Wireless Communication
The evolution of wireless technology has brought much
advancement with its effective features:

The transmitted distance can be anywhere between a
few meters (for example, a television's remote control)
and thousands of kilometres (for example, radio
communication);

Wireless communication can be used for cellular
telephony, wireless access to the Internet, wireless
home networking and so on;

Other examples of applications of radio wireless
technology include GPS units, garage door openers,
wireless computer mice, keyboards and headsets,
headphones, radio receivers, satellite television,
broadcast television and cordless telephones.
8
Wireless Communication — Internet
The advent of the Internet has caused a revolutionary change
in the use of computers and the search for information. The
Internet has affected the traditional way of information
exchange and now almost every city, every town and every
street has access to the Internet.
Homes, schools and businesses connect to the Internet today
using a variety of different methods. One method, wireless
Internet service, provides Internet access to customers without
the need for underground copper, fiber or other forms of
commercial network cabling. Compared to more established
wired services like DSL and cable Internet, wireless technology
brings added convenience and mobility to computer networks.
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The below sections describe each popular type of wireless
Internet service available.
8.1
Satellite Internet
Introduced in the mid-1990s, satellite became the first
mainstream consumer wireless Internet service. Compared to
other forms of wireless Internet service, satellite enjoys the
advantage of availability. Requiring only a small dish antenna,
satellite modem and subscription plan, satellite works in almost
all rural areas not serviced by other technologies.
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However, satellite also offers relatively low performing wireless
Internet. Satellite suffers from high latency (delay) connections
due to the long distance signals must travel between Earth and
the orbiting stations. Satellite also supports relatively modest
amounts of network bandwidth.
8.1.1
Public Wi-Fi Networks
Some municipalities have built their public wireless Internet
service using Wi-Fi technology. These so-called mesh
networks join numerous wireless access points together to
span larger urban areas. Individual Wi-Fi hotspots also provide
public wireless Internet service in select locations.
Wi-Fi is a low-cost option relative to other forms of wireless
Internet service. Equipment is inexpensive (many newer
computers have the needed hardware built in) and Wi-Fi
hotspots remain free in some locales.
8.1.2
Fixed Wireless Broadband
Fixed wireless is a type of broadband that utilises mounted
antennas pointed at radio transmission towers.
8.1.3
Mobile Broadband
Cell phones have existed for decades, but only recently have
cellular networks evolved to become a mainstream form of
wireless Internet service. With an installed cellular network
adapter or by tethering a cell phone to a laptop computer,
Internet connectivity can be maintained in any area with cell
tower coverage. Mobile broadband service will not function
without having an Internet data subscription in place from
some provider.
The classical wired networks have given rise to a number of
application protocols such as TELNET, FTP and SMTP. The
Wireless Application Protocol (WAP) architecture aims at
bridging the gap at the application level, between the wireless
users and the services offered to them.
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Wireless Internet
Wireless Internet refers to the extension of the services offered
by the Internet to mobile users, enabling them to access
information and data irrespective of their location. The inherent
problems associated with wireless domain, mobility of nodes
and the design of existing protocols used in the Internet,
require several solutions for making the wireless Internet a
reality.
The major issues that are to be considered for Wireless
Internet are the following:

Address mobility;

Inefficiency of transport layer protocols; and

Inefficiency of application layer protocols.
8.2.1
Address Mobility
The network layer protocol used in the Internet is Internet
Protocol (IP) which was designed for wired networks with fixed
nodes. IP employs a hierarchical addressing with a globally
unique 32-bit address which has two parts Network identifier
and Host identifier.
The network identifier refers to the subnet address to which the
host is connected. The addressing scheme was used to
reduce the routing table size in the core routers of the Internet,
which uses only the network part of the IP address for making
routing decisions. This addressing scheme may not work
directly in the wireless extension of the Internet, as the mobile
hosts may move from one subnet to another, but the packets
addressed to the mobile host may be delivered to the old
subnet to which the node was originally attached.
8.2.2
Inefficiency of Transport Layer Protocols
The transport layer is very important in the Internet and it
ensures setting up and maintaining end-to-end connections,
reliable end-to-end delivery of data packets, flow control and
congestion control. TCP is the predominant transport layer
protocol for wired networks, even though UDP, a
connectionless, unreliable transport layer protocol is used by
certain applications.
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Wireless Internet requires efficient operation of the transport
layer protocols as the wireless medium is inherently unreliable
due to its time varying and environment dependent
characteristics. Traditional TCP invokes a congestion control
algorithm in order to handle congestion in the networks. If a
data packet or an ACK packet is lost, then TCP assumes that
the loss is due to congestion and reduces the size of the
congestion window by half.
With every successive packet loss, the congestion window is
reduced and hence TCP provides a degraded performance in
wireless links. Even in situations where the packet loss is
caused by link error or collision, the TCP invokes the
congestion control algorithm leading to very low throughput.
The identification of the real cause that led to the packet loss is
important in improving the performance of the TCP over
wireless links. Some of the solutions for the transport layer
issues include:

Indirect TCP (ITCP);

Snoop TCP; and

Mobile TCP.
8.2.3
Inefficiency of Application Layer Protocols
Traditional application layer protocols used in the Internet such
as HTTP, TELNET, Simple Mail Transfer Protocol (SMTP) and
several mark-up languages such as HTML, were designed and
optimised for wired networks. Many of these protocols are not
very efficient when used with wireless links.
The major issues that prevent HTTP from being used in
Wireless Internet is its stateless operation, high overhead due
to character encoding, redundant information carried in the
HTTP requests and opening of a new TCP connection with
every transaction.
The capabilities of the handheld devices are limited, making it
difficult to handle computationally and bandwidth wise
expensive application protocols. Wireless Application Protocol
(WAP) optimisations over traditional HTTP are some of the
solutions for the application layer issues.
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How to Access your Computer Files
from Anywhere
Do you wish to access your personal documents remotely,
music/ videos, photos stored on your personnel computer or
on your mobile phone while you are travelling or when you are
in office? The simplest solution is to copy all your data from the
source to a portable hard drive and then carry it around.
However, this is a cumbersome approach as you would require
manually syncing the home computer with your portable disk.
There are many other innovative ways these days. In this
article, let us explore some technologies and tools to make this
job easier, whenever and wherever you need them.
8.3.1
Desktop Sharing Softwares
Free desktop sharing software such as UltraVNC and
TeamViewer, helps in remotely accessing all your computer
files from anywhere else. Another product with similar features
is LogMein Pro. With these tools, you can transfer files from a
remote computer.
These desktop sharing softwares would help you access all
your files, but one major limitation is that it does require the
remote computer to stay on. Another limitation is that none of
these options will help you access the file on the mobile phone
except LogMeIn, which has iPhone app.
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VPN Server
You can also set up VPN server on your home network and
connect to that. This will allow you to access shared Windows
folders as well as other network storage devices, which would
only be accessible on the local network.
8.3.3
Dedicated Routers and NAS Devices
Few dedicated NAS (Network Attached Storage) devices tend
to support integration for accessing your varied files on the
Internet. Your NAS device’s web interface might not be secure
if it is designed for access over a secure local network. Hence,
do some prior research to ensure that, your NAS or router’s
Internet file sharing features are secure.
8.3.4
Online Backup Services
There are few online backup service providers such as
SugarSync, SkyDrive, Carbonite and Dropbox which offer
desktop utilities that will automatically upload files on your
home computer to the Internet. The major benefits of using
them are that your files will always be available to you even if
the home computer is not running. Both Carbonite and
SugarSync have the mobile-optimised website, which you can
access the file from any mobile phone as well.
8.3.5
FTP Servers
You can also install a FTP (File Transfer Protocol) server on
your computer and provide access to it from the Internet.
From the point of security, it may not be an ideal option since
you would expose the FTP server to the Internet. You can
also set up both a FTP server and VPN, accessing the FTP
server through VPN.
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Cloud Storage Services
As part of Windows Live Mesh application, Microsoft earlier
offered a remote file fetching solution that allows the users to
access PC files over the Internet. They have discontinued this
product for SkyDrive, now known as OneDrive.
Similar to Dropbox and Google Drive, OneDrive is a cloud
storage solution that offers you a special folder on your PC.
Files, as well as folders you place in the folder, are uploaded to
your cloud storage account online and synced to your entire
PC. You can access via your browser or through mobile app.
Microsoft discontinued Windows Live Mesh, because they
started believing cloud storage service is an ideal option for
any average user to access their files. You also need not have
your PC online, install the server software or use a dedicated
device. However, you cannot access any file on your PC, but
you need to sync the files you care for and access them.
8.3.7
Access Files Directly through the Browser
Online backup services would copy files to their servers,
before you can access them from anywhere else. We find
screen sharing services are often slow and they do not work
on numerous mobile devices.
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Like Google Desktop, Copernic is a popular software for
desktop search, wherein you can use it to find documents,
emails and other files on your Windows computer. They tend
to have paid component called myCopernic on the go. This
allows you to remotely search for varied content stored on
home or office computer.
8.3.8
Opera Unite
With Opera Unite, you can very well turn your computer into a
web server and instantly access files as well as the folders on
the computer from any other web browser.
8.3.9
GBridge
Another best option is GBridge; it allows you to setup a virtual
private network by using your existing Google Account.
Companies tend to use VPNs to let employees access
corporate data over the public network; even the home users
can build their VPNs to access remote files more securely.
8.3.10 Windows Live Sync
Windows Live Sync is another good choice for remotely
accessing files over the Internet. You require to install the Live
Sync client on your computer, after that, you would be able to
access the entire hard drive of the computer through the
Windows Live Sync Website.
8.3.11 HomePipe
Lastly, check out HomePipe, which is currently available for
free and allows you to access home files as well as media from
any other computer or mobile phone. It has apps for both
Android phones as well as iPhones.
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Chapter 3: Network Addressing
1
What is Network?
This era is said to be the era of computers. Computers have
significantly changed the way we live. A computing device
when connected to other computing devices enables us to
share data and information at lightning-fast speed.
A Network in the world of computers is said to be a collection
of interconnected hosts, via some shared media which can be
wired or wireless. A computer network enables its hosts to
share and exchange data and information over the media.
Network can be a Local Area Network spanned across an
office, Metro Area Network spanned across a city or Wide Area
Network which can be spanned across cities and provinces.
A computer network can be as simple as two PCs connected
together via a single copper cable or it can be grown up to the
complexity where every computer in this world is connected to
every other, called the Internet. A network then includes more
and more components to reach its ultimate goal of data
exchange.
Below is a brief description of the components involved in
computer network:

Hosts — Hosts are said to be situated at either end of
the network, i.e. a host is a source of information and
another host will be the destination. Information flows
end to end between hosts. A host can be a user’s PC,
an Internet server, a database server, etc.;

Media — If wired, then it can be copper cable, fiber optic
cable and coaxial cable. If wireless, it can be free-to-air
radio frequency or some special wireless band. Wireless
frequencies can be used to interconnect remote sites
too;

Hub — A hub is a multiport repeater and it is used to
connect hosts in a LAN segment. Because of low
throughputs hubs are now rarely used. Hub works on
Layer-1 (Physical Layer) of OSI Model;

Switch — A Switch is a multiport bridge and is used to
connect hosts in a LAN segment. Switches are much
faster than Hubs and operate on wire speed. Switch
works on Layer-2 (Data Link Layer), but Layer-3
(Network Layer) switches are also available;
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

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Router —A router is Layer-3 (Network Layer) device
which makes routing decisions for the data/ information
sent for some remote destination. Routers make the
core of any interconnected network and the Internet;
Gateways —A software or combination of software and
hardware put together, works for exchanging data
among networks which are using different protocols for
sharing data;
Firewall —Software or combination of software and
hardware, used to protect users data from unintended
recipients on the network/ Internet.
All components in a network ultimately serve the hosts.
1.1
Host Addressing
Communication between hosts can happen only if they can
identify each other on the network. In a single collision domain
(where every packet sent on the segment by one host is heard
by every other host), hosts can communicate directly via MAC
address.
MAC address is a factory coded 48-bit hardware address
which can also uniquely identify a host. But if a host wants to
communicate with a remote host, i.e. not in the same segment
or logically not connected, then some means of addressing is
required to identify the remote host uniquely. A logical address
is given to all hosts connected to Internet and this logical
address is called Internet Protocol Address.
2
Internet Protocol Address and
Addressing
2.1
IPv4 Supports Three Different Types of
Addressing Modes
2.1.1
Unicast Addressing Mode
In this mode, data is sent only to one destined host. The
Destination Address field contains 32-bit IP address of the
destination host.
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Here the client sends data to the targeted server:
2.1.2
Broadcast Addressing Mode
In this mode, the packet is addressed to all the hosts in a
network segment. The Destination Address field contains a
special broadcast address, i.e. 255.255.255.255. When a host
sees this packet on the network, it is bound to process it.
Here the client sends a packet, which is entertained by all the
Servers:
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Multicast Addressing Mode
This mode is a mix of the previous two modes, i.e. the packet
sent is neither destined to a single host nor all the hosts on the
segment. In this packet, the Destination Address contains a
special address which starts with 224.x.x.x and can be
entertained by more than one host.
Here a server sends packets which are entertained by more
than one server. Every network has one IP address reserved
for the Network Number which represents the network and one
IP address reserved for the Broadcast Address, which
represents all the hosts in that network.
2.2
Hierarchical Addressing Scheme
IPv4 uses hierarchical addressing scheme. An IP address,
which is 32-bits in length, is divided into two or three parts as
depicted:
A single IP address can contain information about the network
and its sub-network and ultimately the host. This scheme
enables the IP Address to be hierarchical where a network can
have many sub-networks which in turn can have many hosts.
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Subnet Mask
The 32-bit IP address contains information about the host and
its network. It is very necessary to distinguish both. For this,
routers use Subnet Mask, which is as long as the size of the
network address in the IP address. Subnet Mask is also 32 bits
long. If the IP address in binary is ANDed with its Subnet
Mask, the result yields the Network address.
For example, say the IP Address is 192.168.1.152 and the
Subnet Mask is 255.255.255.0 then:
This way the Subnet Mask helps extract the Network ID and
the Host from an IP Address. It can be identified now that
192.168.1.0 is the Network number and 192.168.1.152 is the
host on that network.
3
Binary Representation
The positional value method is the simplest form of converting
binary from decimal value. IP address is 32-bit value which is
divided into four octets. A binary octet contains eight bits and
the value of each bit can be determined by the position of bit
value '1' in the octet.
Positional value of bits is determined by two raised to power
(position — 1), that is the value of a bit one at position six is
2^(6-1) that is 2^5 that is 32. The total value of the octet is
determined by adding up the positional value of bits. The value
of 11 000 000 is 128+64 = 192.
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Some examples are shown in the table below:
3.1
IPv4 — Address Classes
Internet Protocol hierarchy contains several classes of IP
Addresses to be used efficiently in various situations as per the
requirement of hosts per network. Broadly, the IPv4
Addressing system is divided into five classes of IP Addresses.
All the five classes are identified by the first octet of IP
Address. Internet Corporation for Assigned Names and
Numbers is responsible for assigning IP addresses.
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The first octet referred here is the left most of all. The octets
numbered as follows depicting dotted decimal notation of IP
Address:
The number of networks and the number of hosts per class
can be derived by this formula:
When calculating hosts' IP addresses, two IP addresses are
decreased, because they cannot be assigned to hosts, i.e. the
first IP of a network is network number and the last IP is
reserved for Broadcast IP.
3.1.1
Class A Address
The first bit of the first octet is always set to 0 (zero). Thus the
first octet ranges from 1 — 127, i.e.:
Class A addresses only include IP starting from 1.x.x.x to
126.x.x.x only. The IP range 127.x.x.x is reserved for loopback
IP addresses.
The default subnet mask for Class A IP address is 255.0.0.0
which implies that Class A addressing can have 126 networks
(27-2) and 16777214 hosts (224-2).
Class
A
IP
address
format
is
0NNNNNNN.HHHHHHHH.HHHHHHHH.HHHHHHHH
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Class B Address
An IP address which belongs to class B has the first two bits in
the first octet set to 10, i.e.:
Class B IP Addresses range from 128.0.x.x to 191.255.x.x.
The default subnet mask for Class B is 255.255.x.x.
Class B has 16384 (214) Network addresses and 65534 (216-2)
Host addresses.
Class
B
IP
address
format
10NNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH
3.1.3
is:
Class C Address
The first octet of Class C IP address has its first 3 bits set to
110, that is:
Class C IP addresses range from 192.0.0.x to 223.255.255.x.
The default subnet mask for Class C is 255.255.255.x.
Class C gives 2097152 (221) Network addresses and 254 (282) Host addresses.
Class
C
IP
address
format
110NNNNN.NNNNNNNN.NNNNNNNN.HHHHHHHH
3.1.4
is:
Class D Address
Very first four bits of the first octet in Class D IP addresses are
set to 1110, giving a range of:
Class D has IP address rage from 224.0.0.0
239.255.255.255. Class D is reserved for Multicasting.
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In multicasting data is not destined for a particular host, that is
why there is no need to extract host address from the IP
address and Class D does not have any subnet mask.
3.1.5
Class E Address
This IP Class is reserved for experimental purposes only for
R&D or Study. IP addresses in this class ranges from
240.0.0.0 to 255.255.255.254. Like Class D, this class too is
not equipped with any subnet mask.
3.2
IPv4 — Subnetting
Each IP class is equipped with its own default subnet mask
which bounds that IP class to have a prefixed number of
Networks and a prefixed number of Hosts per network.
Classful IP addressing does not provide any flexibility of having
less number of Hosts per Network or more Networks per IP
Class.
CIDR or Classless Inter Domain Routing provides the flexibility
of borrowing bits of Host part of the IP address and using them
as Network in Network, called Subnet. By using subnetting,
one single Class A IP address can be used to have smaller
sub-networks which provides better network management
capabilities.
3.2.1
Class A Subnets
In Class A, only the first octet is used as Network identifier and
rest of the three octets are used to be assigned to Hosts (i.e.
16777214 Hosts per Network). To make more subnet in Class
A, bits from Host part are borrowed and the subnet mask is
changed accordingly.
For example, if one MSB (Most Significant Bit) is borrowed
from host bits of second octet and added to Network address,
it creates two Subnets (21=2) with (223-2) 8388606 Hosts per
Subnet.
The Subnet mask is changed accordingly to reflect subnetting.
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Given below is a list of all possible combination of Class A
subnets:
In case of subnetting too, the very first and last IP address of
every subnet is used for Subnet Number and Subnet
Broadcast IP address respectively. Because these two IP
addresses cannot be assigned to hosts, subnetting cannot be
implemented by using more than 30 bits as Network Bits,
which provides less than two hosts per subnet.
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Class B Subnets
By default, using Classful Networking, 14 bits are used as
Network bits providing (214) 16384 Networks and (216-2) 65534
Hosts. Class B IP Addresses can be subnetted the same way
as Class A addresses, by borrowing bits from Host bits.
Below is given all possible combination of Class B subnetting:
3.2.3
Class C Subnets
Class C IP addresses are normally assigned to a very small
size network because it can only have 254 hosts in a network.
Given below is a list of all possible combination of subnetted
Class B IP address:
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IPv4 — VLSM
Internet Service Providers may face a situation where they
need to allocate IP subnets of different sizes as per the
requirement of customer. One customer may ask Class C
subnet of three IP addresses and another may ask for 10 IPs.
For an ISP, it is not feasible to divide the IP addresses into
fixed size subnets; rather he/ she may want to subnet the
subnets in such a way which results in minimum wastage of IP
addresses.
For example, an administrator have 192.168.1.0/24 network.
The suffix /24 (pronounced as "slash 24") tells the number of
bits used for network address. In this example, the
administrator has three different departments with different
number of hosts. Sales department has 100 computers,
Purchase department has 50 computers, Accounts has
25 computers and Management has five computers. In CIDR,
the subnets are of fixed size. Using the same methodology the
administrator cannot fulfil all the requirements of the network.
The following procedure shows how VLSM can be used in
order to allocate department-wise IP addresses as mentioned
in the example.
3.3.1
Step 1
Make a list of Subnets possible.
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Step 2
Sort the requirements of IPs in descending order (Highest to
Lowest).

Sales — 100;

Purchase — 50;

Accounts — 25;

Management — 5.
3.3.3
Step 3
Allocate the highest range of IPs to the highest requirement, so
let us assign 192.168.1.0 /25 (255.255.255.128) to the Sales
department. This IP subnet with Network number 192.168.1.0
has 126 valid Host IP addresses which satisfy the requirement
of the Sales department. The subnet mask used for this subnet
has 10000000 as the last octet.
3.3.4
Step 4
Allocate the next highest range, so let us assign 192.168.1.128
/26 (255.255.255.192) to the Purchase department. This IP
subnet with Network number 192.168.1.128 has 62 valid Host
IP Addresses which can be easily assigned to all the PCs of
the Purchase department. The subnet mask used has
11000000 in the last octet.
3.3.5
Step 5
Allocate the next highest range, i.e. Accounts. The requirement
of 25 IPs can be fulfilled with 192.168.1.192 /27
(255.255.255.224) IP subnet, which contains 30 valid host IPs.
The network number of Accounts department will be
192.168.1.192. The last octet of subnet mask is 11100000.
3.3.6
Step 6
Allocate the next highest range to Management. The
Management department contains only five computers. The
subnet 192.168.1.224 /29 with the Mask 255.255.255.248 has
exactly six valid host IP addresses. So this can be assigned to
Management. The last octet of the subnet mask will contain
11111000.
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By using VLSM, the administrator can subnet the IP subnet in
such a way that the least number of IP addresses are wasted.
Even after assigning IPs to every department, the
administrator, in this example, is still left with plenty of IP
addresses which were not possible if he/ she has used CIDR.
3.4
IPv4 — Reserved Addresses
There are a few reserved IPv4 address spaces which cannot
be used on the Internet. These addresses serve a special
purpose and cannot be routed outside the Local Area Network.
3.5
Private IP Addresses
Every class of IP (A, B and C) have some addresses reserved
as Private IP addresses. These IPs can be used within a
network, campus, company and are private to it. These
addresses cannot be routed on the Internet, so packets
containing these private addresses are dropped by the
Routers.
In order to communicate with the outside world, these IP
addresses have to be translated to some public IP addresses
using NAT process or a Web Proxy server can be used.
The sole purpose to create a separate range of private
addresses is to control assignment of already-limited IPv4
address pool. By using a private address range within LAN, the
requirement of IPv4 addresses has globally decreased
significantly. It has also helped delay the IPv4 address
exhaustion.
IP class, while using private address range, can be chosen as
per the size and requirement of the organisation. Larger
organisations may choose Class A private IP address range
where smaller organisations may opt for Class C. These IP
addresses can be further subnetted and assigned to
departments within an organisation.
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Loopback IP Addresses
The IP address range 127.0.0.0 — 127.255.255.255 is
reserved for loopback, i.e. a Host’s self-address, also known
as localhost address. This loopback IP address is managed
entirely by and within the operating system. Loopback
addresses enable the Server and Client processes on a single
system to communicate with each other. When a process
creates a packet with a destination address such as a
loopback address, the operating system loops it back to itself
without having any interference of NIC.
Data sent on loopback is forwarded by the operating system to
a virtual network interface within an operating system. This
address is mostly used for testing purposes like client-server
architecture on a single machine. Other than that, if a host
machine can successfully ping 127.0.0.1 or any IP from the
loopback range, it implies that the TCP/IP software stack on
the machine is successfully loaded and working.
3.7
Link-local Addresses
In case a host is not able to acquire an IP address from the
DHCP server and it has not been assigned any IP address
manually, the host can assign itself an IP address from a range
of reserved Link-local addresses. Link local address ranges
from 169.254.0.0 — 169.254.255.255.
Assume a network segment, where all systems are configured
to acquire IP addresses from a DHCP server, are connected to
the same network segment. If the DHCP server is not
available, no host on the segment will be able to communicate
to any other. Windows (98 or later) and Mac OS (8.0 or later)
support this functionality of self-configuration of Link-local IP
address. In absence of DHCP server, every host machine
randomly chooses an IP address from the above mentioned
range and then checks to ascertain by means of ARP, if some
other host also has not configured itself with the same IP
address. Once all hosts are using link-local addresses of same
range, they can communicate with each other.
These IP addresses cannot help the system to communicate
when they do not belong to the same physical or logical
segment. These IPs are also not routable.
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IPv6 — Overview
Internet Protocol version 6 is a new addressing protocol
designed to incorporate all the possible requirements of future
Internet known to us as Internet version 2. This protocol as its
predecessor IPv4, works on the Network Layer (Layer-3).
Along with its offering of an enormous amount of logical
address space, this protocol has ample features to which
address the shortcoming of IPv4.
4.1
Why New IP Version?
So far, IPv4 has proven itself as a robust routable addressing
protocol and has served us for decades on its best-effortdelivery mechanism. It was designed in the early 80s and did
not get any major change afterward. At the time of its birth, the
Internet was limited only to a few universities for their research
and to the Department of Defense. IPv4 is 32-bits long and
offers around 4 294 967 296 (232) addresses. This address
space was considered more than enough that time.
Given below are the major points that played a key role in the
birth of IPv6:

Internet has grown exponentially and the address space
allowed by IPv4 is saturating. There is a requirement to
have a protocol that can satisfy the needs of future
Internet addresses that is expected to grow in an
unexpected manner;

IPv4 on its own does not provide any security feature.
Data has to be encrypted with some other security
application before being sent on the Internet;

Data prioritisation in IPv4 is not up to date. Though IPv4
has a few bits reserved for Type of Service or Quality of
Service, they do not provide much functionality;

IPv4 enabled clients can be configured manually or they
need some address configuration mechanism. It does
not have a mechanism to configure a device to have
globally unique IP address.
4.2
Why Not IPv5?
Till date, Internet Protocol has been recognised has IPv4 only.
Versions zero to three were used while the protocol was itself
under development and experimental process. So, we can
assume lots of background activities remain active before
putting a protocol into production.
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Similarly, protocol version five was used while experimenting
with the stream protocol for Internet. It is known to us as
Internet Stream Protocol which used Internet Protocol number
five to encapsulate its datagram. It was never brought into
public use, but it was already used.
Here is a table of IP versions and how they are used:
4.3
Brief History
After IPv4’s development in the early 80s, the available IPv4
address pool begun to shrink rapidly as the demand of
addresses exponentially increased with Internet. Taking precognisance of the situation that might arise, IETF, in 1994,
initiated the development of an addressing protocol to replace
IPv4.
The progress of IPv6 can be tracked by means of the RFC
published:

1998 — RFC 2460 — Basic Protocol;

2003 — RFC 2553 — Basic Socket API;

2003 — RFC 3315 — DHCPv6;

2004 — RFC 3775 — Mobile IPv6;

2004 — RFC 3697 — Flow Label Specification;

2006 — RFC 4291 — Address architecture (revision);

2006 — RFC 4294 — Node requirement.
On June 6, 2012, some of the Internet giants chose to put their
Servers on IPv6. Presently they are using Dual Stack
mechanism to implement IPv6 parallel in with IPv4.
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IPv6 — Features
The successor of IPv4 is not designed to be backward
compatible. Trying to keep the basic functionalities of IP
addressing, IPv6 is redesigned entirely.
It offers the following features:

Larger Address Space
In contrast to IPv4, IPv6 uses four times more bits to
address a device on the Internet. This much of extra bits
can provide approximately 3.4 × 1 038 different
combinations of addresses. This address can
accumulate the aggressive requirement of address
allotment for almost everything in this world. According
to an estimate, 1 564 addresses can be allocated to
every square meter of this earth.

Simplified Header
IPv6’s header has been simplified by moving all
unnecessary information and options (which are present
in IPv4 header) to the end of the IPv6 header. IPv6
header is only twice as big as IPv4 provided the fact that
IPv6 address is four times longer.

End-to-end Connectivity
Every system now has unique IP address and can
traverse through the Internet without using NAT or other
translating components. After IPv6 is fully implemented,
every host can directly reach other hosts on the Internet,
with some limitations involved like Firewall, organisation
policies, etc.

Auto-configuration
IPv6 supports both stateful and stateless auto
configuration mode of its host devices. This way,
absence of a DHCP server does not put a halt on inter
segment communication.

Faster Forwarding/ Routing
Simplified header puts all unnecessary information at
the end of the header. The information contained in the
first part of the header is adequate for a Router to make
routing decisions, thus making routing decision as
quickly as looking at the mandatory header.
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
IPSec
Initially it was decided that IPv6 must have IPSec
security, making it more secure than IPv4. This feature
has now been made optional.

No Broadcast
Though Ethernet/ Token Ring is considered as
broadcast network because they support Broadcasting,
IPv6 does not have any broadcast support any more. It
uses multicast to communicate with multiple hosts.

Anycast Support
This is another characteristic of IPv6. IPv6 has
introduced Anycast mode of packet routing. In this
mode, multiple interfaces over the Internet are assigned
same Anycast IP address. Routers, while routing, send
the packet to the nearest destination.

Mobility
IPv6 was designed keeping mobility in mind. This
feature enables hosts (such as mobile phone) to roam
around in different geographical area and remain
connected with the same IP address. The mobility
feature of IPv6 takes advantage of auto IP configuration
and Extension headers.

Enhanced Priority Support
IPv4 used six bits DSCP (Differential Service Code
Point) and two bits ECN (Explicit Congestion
Notification) to provide Quality of Service, but it could
only be used if the end-to-end devices support it, that is,
the source and destination device and underlying
network must support it. In IPv6, Traffic class and Flow
label are used to tell the underlying routers how to
efficiently process the packet and route it.

Smooth Transition
Large IP address scheme in IPv6 enables to allocate
devices with globally unique IP addresses. This
mechanism saves IP addresses and NAT is not
required. So devices can send/ receive data among
each other, for example, VoIP and/ or any streaming
media can be used much efficiently. Other fact is the
header is less loaded, so routers can make forwarding
decisions and forward them as quickly as they arrive.
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Extensibility
One of the major advantages of IPv6 header is that it is
extensible to add more information in the option part.
IPv4 provides only 40-bytes for options, whereas options
in IPv6 can be as much as the size of IPv6 packet itself.
IPv6 — Addressing Modes
In computer networking, addressing mode refers to the
mechanism of hosting an address on the network. IPv6 offers
several types of modes by which a single host can be
addressed. More than one host can be addressed at once or
the host at the closest distance can be addressed.
4.5.1
Unicast
In unicast mode of addressing, an IPv6 interface (host) is
uniquely identified in a network segment. The IPv6 packet
contains both source and destination IP addresses. A host
interface is equipped with an IP address which is unique in that
network segment. When a network switch or a router receives
a unicast IP packet, destined to a single host, it sends out one
of its outgoing interface which connects to that particular host.
4.5.2
Multicast
The IPv6 multicast mode is same as that of IPv4. The packet
destined to multiple hosts is sent on a special multicast
address. All the hosts interested in that multicast information,
need to join that multicast group first.
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All the interfaces that joined the group receive the multicast
packet and process it, while other hosts not interested in
multicast packets ignore the multicast information.
4.5.3
Anycast
IPv6 has introduced a new type of addressing, which is called
Anycast addressing. In this addressing mode, multiple
interfaces (hosts) are assigned same Anycast IP address.
When a host wishes to communicate with a host equipped with
an Anycast IP address, it sends a Unicast message. With the
help of complex routing mechanism, that Unicast message is
delivered to the host closest to the Sender in terms of Routing
cost.
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Let us take an example of TutorialPoints.com Web Servers,
located on all continents. Assume that all the Web Servers are
assigned a single IPv6 Anycast IP Address. Now when a user
from Europe wants to reach TutorialsPoint.com, the DNS
points to the server that is physically located in Europe itself. If
a user from India tries to reach Tutorialspoint.com, the DNS
will then point to the Web Server physically located in Asia.
Nearest or closest terms are used in terms of Routing Cost.
In the above picture, when a client computer tries to reach a
server, the request is forwarded to the server with the lowest
Routing Cost.
4.6
IPv6 — Special Addresses
Version 6 has a slightly complex structure of IP address than
that of IPv4. IPv6 has reserved a few addresses and address
notations for special purposes. See the table below:



As shown in the table, the address 0:0:0:0:0:0:0:0/128
does not specify anything and is said to be an
unspecified address. After simplifying, all the 0s are
compacted to ::/128;
In IPv4, the address 0.0.0.0 with netmask 0.0.0.0
represents the default route. The same concept is also
applied to IPv6, address 0:0:0:0:0:0:0:0 with netmask all
0s represents the default route. After applying IPv6 rule,
this address is compressed to ::/0;
Loopback addresses in IPv4 are represented by
127.0.0.1 to 127.255.255.255 series. But in IPv6, only
0:0:0:0:0:0:0:1/128 represents the Loopback address.
After loopback address, it can be represented as
::1/128.
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

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Reserved Multicast Address for Routing
Protocols
The above table shows the reserved multicast
addresses used by interior routing protocol;
The addresses are reserved following the same rules of
IPv4.
Reserved Multicast Address for Routers/
Node
These addresses help routers and hosts to speak to available
routers and hosts on a segment without being configured with
an IPv6 address. Hosts use EUI-64 based auto-configuration
to self-configure an IPv6 address and then speak to available
hosts/ routers on the segment by means of these addresses.
4.9
IPv6 — Subnetting
In IPv4, addresses were created in classes. Classful IPv4
addresses clearly define the bits used for network prefixes and
the bits used for hosts on that network. To subnet in IPv4, we
play with the default classful netmask which allows us to
borrow host bits to be used as subnet bits. This results in
multiple subnets, but less hosts per subnet. That is, when we
borrow host bits to create a subnet, it costs us in lesser bit to
be used for host addresses.
IPv6 addresses use 128 bits to represent an address which
includes bits to be used for subnetting. The second half of the
address (least significant 64 bits) is always used for hosts only.
Therefore, there is no compromise if we subnet the network.
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16 bits of subnet is equivalent to IPv4’s Class B Network.
Using these subnet bits, an organisation can have another 65
thousands of subnets which is by far more than enough.
Thus routing prefix is /64 and host portion is 64 bits. We can
further subnet the network beyond 16 bits of Subnet ID, by
borrowing host bits; but it is recommended that 64 bits should
always be used for hosts addresses because autoconfiguration requires 64 bits.
IPv6 subnetting works on the same concept as Variable
Length Subnet Masking in IPv4.
/48 prefix can be allocated to an organisation providing it the
benefit of having up to /64 subnet prefixes, which is 65535
sub-networks, each having 264 hosts. A /64 prefix can be
assigned to a point-to-point connection where there are only
two hosts (or IPv6 enabled devices) on a link.
5
Transition from IPv4 to IPv6
Complete transition from IPv4 to IPv6 might not be possible
because IPv6 is not backward compatible. This results in a
situation where either a site is on IPv6 or it is not. It is unlike
the implementation of other new technologies where the newer
one is backward compatible so the older system can still work
with the newer version without any additional changes.
To overcome this short-coming, we have a few technologies
that can be used to ensure slow and smooth transition from
IPv4 to IPv6.
5.1
Dual Stack Routers
A router can be installed with both IPv4 and IPv6 addresses
configured on its interfaces pointing to the network of relevant
IP scheme.
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[Image: Dual Stack Router]
In the above diagram, a server having IPv4 as well as IPv6
address configured for it can now speak with all the hosts on
both the IPv4 as well as the IPv6 networks with the help of a
Dual Stack Router. The Dual Stack Router can communicate
with both the networks. It provides a medium for the hosts to
access a server without changing their respective IP versions.
5.2
Tunneling
In a scenario where different IP versions exist on intermediate
path or transit networks, tunneling provides a better solution
where user’s data can pass through a non-supported IP
version.
The above diagram depicts how two remote IPv4 networks can
communicate via a Tunnel, where the transit network was on
IPv6. Vice versa is also possible where the transit network is
on IPv6 and the remote sites that intend to communicate are
on IPv4.
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NAT Protocol Translation
This is another important method of transition to IPv6 by
means of a NAT-PT (Network Address Translation — Protocol
Translation) enabled device. See the diagram below:
A host with IPv4 address sends a request to an IPv6 enabled
server on the Internet that does not understand IPv4 address.
In this scenario, the NAT-PT device can help them
communicate. When the IPv4 host sends a request packet to
the IPv6 server, the NAT-PT device/ router strips down the
IPv4 packet, removes IPv4 header, adds IPv6 header and
passes it through the Internet. When a response from the IPv6
server comes for the IPv4 host, the router does vice versa.
6
Future of IPv6
IPv6 enabled Internet version 2 will replace todays IPv4
enabled Internet. When the Internet was launched with IPv4,
developed countries like the U.S. and Europe took the larger
space of IPv4 for deployment of Internet in their respective
countries keeping the future need in mind. But the Internet
exploded everywhere reaching and connecting every country
of the world increasing the requirement of IPv4 address space.
As a result, till this day the U.S. and Europe have many IPv4
address space left with them and countries like India and
China are bound to address their IP space requirement by
means of deployment of IPv6.
Most of the IPv6 deployment is being done outside the U.S.
and Europe. India and China are moving forward to change
their entire space to IPv6. China has announced a five-year
deployment plan named China Next Generation the Internet.
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After June 06, 2012 all major ISPs were shifted to IPv6 and
rest of them are still moving.
IPv6 provides ample address space and is designed to expand
today’s Internet services. Feature-rich IPv6 enabled Internet
version 2 may deliver more than expected.
7
Network Services
Computer systems and computerised systems help human
beings to work efficiently and explore the unthinkable. When
these devices are connected together to form a network, the
capabilities are enhanced multiple-times. Some basic services
computer network can offer are:
7.1
Directory Services
These services are mapping between name and its value,
which can be variable value or fixed. This software system
helps to store the information, organise it and provides various
means of accessing it.

Accounting
In an organisation, a number of users have their user
names and passwords mapped to them. Directory
Services provide means of storing this information in
cryptic form and make available when requested.

Authentication and Authorisation
User credentials are checked to authenticate a user at
the time of login and/ or periodically. User accounts can
be set into hierarchical structure and their access to
resources can be controlled using authorisation
schemes.

Domain Name Services
DNS is widely used and one of the essential services on
which the Internet works. This system maps IP
addresses to domain names, which are easier to
remember than IP addresses. Because networks
operate with the help of IP addresses and humans tend
to remember website names, the DNS provides
website’s IP address which is mapped to its name from
the back-end on the request of a website name from the
user.
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File Services
File services include sharing and transferring files over the
network.

File Sharing
One of the reasons which gave birth to networking was
file sharing. File sharing enables its users to share their
data with other users. Users can upload the file to a
specific server, which is accessible by all intended
users. As an alternative, users can make its file shared
on its own computer and provides access to intended
users.

File Transfer
This is an activity to copy or move file from one
computer to another computer or to multiple computers,
with help of underlying network. Network enables its
user to locate other users in the network and transfers
files.
7.3
Communication Services

Email
Electronic mail is a communication method and
something a computer user cannot work without. This is
the basis of today’s Internet features. Email systems
have one or more email servers. All its users are
provided with unique IDs. When a user sends email to
other user, it is actually transferred between users with
the help of an email server.

Social Networking
Recent technologies have made technical life social.
The computer savvy people can find other known people
or friends, can connect with them and can share
thoughts, pictures and videos.

Internet Chat
Internet chat provides instant text transfer services
between two hosts. Two or more people can
communicate with each other using text-based Internet
Relay Chat services. These days, voice chat and video
chat are very common.
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
Discussion Boards
Discussion boards provide a mechanism to connect
multiple people with the same interests. It enables the
users to put queries, questions, suggestions, etc., which
can be seen by all other users. Other may respond as
well.

Remote Access
This service enables users to access the data residing
on the remote computer. This feature is known as
Remote desktop. This can be done via some remote
device, e.g. mobile phone or home computer.
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Application Services
These are nothing but providing network based services to the
users such as web services, database managing and resource
sharing.

Resource Sharing
To use resources efficiently and economically, network
provides a means to share them. This may include
Servers, Printers and Storage Media, etc.

Databases
This application service is one of the most important
services. It stores data and information, processes it and
enables the users to retrieve it efficiently by using
queries. Databases help organisations to make
decisions based on statistics.

Web Services
World Wide Web has become the synonym for Internet.
It is used to connect to the Internet and access files and
information services provided by the Internet servers.
7.5
Intranet
Intranet is defined as private network of computers within an
organisation with its own server and firewall. Moreover we can
define Intranet as:

Intranet is a system in which multiple PCs are networked
to be connected to each other. PCs in intranets are not
available to the world outside of the intranet;

Usually each company or organisation has their own
Intranet network and members/ employees of that
company can access the computers in their intranet;
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
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Every computer in Internet is identified by a unique IP
address;
Each computer in Intranet is also identified by an IP
Address, which is unique among the computers in that
Intranet.
Benefits
Intranet is a very efficient and reliable network system for any
organisation. It is beneficial in every aspect such as
collaboration, cost-effectiveness, security, productivity and
much more.
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
Communication
Intranet offers easy and cheap communication within an
organisation. Employees can communicate using chat,
email or blogs.

Time Saving
Information on Intranet is shared in real time.

Collaboration
Information is distributed among the employees as
according to requirement and it can be accessed by the
authorised users, resulting in enhanced teamwork.

Platform Independency
Intranet can connect computers and other devices with
different architecture.

Cost Effective
Employees can see the data and other documents using
a browser rather than printing them and distributing
duplicate copies among the employees, which certainly
decreases the cost.

Workforce Productivity
Data is available at every time and can be accessed
using company workstations. This helps the employees
work faster.

Business Management
It is also possible to deploy applications that support
business operations.

Security
Since information shared on intranet can only be
accessed within an organisation, therefore, there is
almost no chance of being stolen.

Specific Users
Intranet targets only specific users within an
organisation, therefore, one can exactly know whom
employees are interacting with.

Immediate Updates
Any changes made to information
immediately to all the users.
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Issues
Apart from several benefits of Intranet, there also exist some
issues. These issues are shown in the following diagram:
7.5.3
Applications
Intranet applications are the same as that of Internet
applications. Intranet applications are also accessed through a
web browser. The only difference is that, Intranet applications
reside on local server while Internet applications reside on
remote server.
Here, we have discussed some of these applications:
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
Document publication applications
Document publication applications allow publishing
documents such as manuals, software guide and
employee profits without use of paper.

Electronic resources applications
It offers electronic resources such as software
applications, templates and tools, to be shared across
the network.

Interactive Communication applications
Like on the Internet, we have email and chat like
applications for Intranet, hence offering an interactive
communication among employees.

Support for Internet Applications
Intranet offers an environment to deploy and test
applications before placing them on the Internet.
7.6
Internet vs. Intranet
Apart from similarities there are some differences between the
two. Following are the differences between Internet and
Intranet:
Intranet
Internet
Localised Network.
Worldwide Network
Does not have access to Intranet
Have access to Internet.
More Expensive
Less Expensive
More Safe
Less Safe
More Reliability
Less Reliability
7.7
Extranet
Extranet refers to a network within an organisation, using
Internet to connect to the outsiders in controlled manner. It
helps to connect businesses with their customers and
suppliers and, therefore, allow working in a collaborative
manner.
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Implementation
Extranet is implemented as a Virtual Private Networks (VPN)
because it uses the Internet to connect to a corporate
organisation and there is always a threat to information
security. VPN offers a secure network in public infrastructure
(Internet).
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Key Points:

The packet is encapsulated at the boundary of networks
in IPSEC complaint routers;

It uses an encryption key to encapsulate packets and IP
addresses as well;

The packet is decoded only by the IPSEC complaint
routers or servers;

The message is sent over VPN via VPN Tunnel and this
process is known as tunneling.
VPN uses Internet Protocol Security Architecture (IPSEC)
Protocol to provide secure transactions by adding an additional
security layer to TCP/IP protocol. This layer is created by
encapsulating the IP packet to a new IP packet as shown in
the following diagram:
7.7.2
Benefits
Extranet proves to be a successful model for all kinds of
businesses whether small or big. Here are some of the
advantages of extranet for employees, suppliers, business
partners and customers:
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Issues
Apart for advantages there are also some issues associated
with extranet. These issues are discussed below:
Hosting
Where will the extranet pages will be held, i.e. who will host the
extranet pages. In this context there are two choices:

Host it on your own server;

Host it with an Internet Service Provider (ISP) in the
same way as web pages.
But hosting extranet pages on your own server requires high
bandwidth Internet connection which is very costly.
Security
Additional firewall security is required if you host extranet
pages on your own server which results in a complex security
mechanism and increase work load.
Accessing Issues
Information cannot be accessed without Internet connection.
However, information can be accessed in Intranet without
Internet connection.
Decreased Interaction
It decreases the face to face interaction in the business which
results in lack of communication among customers, business
partners and suppliers.
7.8
Extranet vs. Intranet
The following table shows differences between Extranet and
Intranet:
Extranet
Intranet
Internal network that can be
accessed externally.
Internal network that cannot be
accessed externally.
Extranet is extension an of
company's Intranet.
Only limited users of a
company.
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Extranet
Intranet
For limited external
communication between
customers, suppliers and
business partners.
Only for communication within
a company.
8
8.1
Internet Domain Name System
Overview
When DNS was not in existence, one had to download a Host
file containing host names and their corresponding IP address.
But with the increase in number of hosts of Internet, the size of
host file also increased. This resulted in increased traffic on
downloading this file. To solve this problem the DNS system
was introduced.
Domain Name System helps to resolve the host name to an
address. It uses a hierarchical naming scheme and distributed
database of IP addresses and associated names.
8.2
IP Address
An IP address is a unique logical address assigned to a
machine over the network. An IP address exhibits the following
properties:

IP address is the unique address assigned to each host
present on the Internet;

IP address is 32 bits (four bytes) long;

IP address consists of two components: network
component and host component;

Each of the four bytes is represented by a number from
zero to 255, separated with dots. For example
137.170.4.124
An IP address is 32-bit number while, on the other hand,
domain names are easy to remember names. For example,
when we enter an email address we always enter a symbolic
string such as webmaster@tutorialspoint.com.
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Uniform Resource Locator (URL)
Uniform Resource Locator (URL) refers to a web address
which uniquely identifies a document over the Internet. This
document can be a web page, image, audio, video or anything
else present on the web.
For example:
www.tutorialspoint.com/Internet_technology/index.html is an
URL to the index.html which is stored on tutorialspoint web
server under Internet_technology directory.
8.4
URL Types
There are two forms of URL as listed below:
1.
Absolute URL
2.
Relative URL
8.4.1
Absolute URL
Absolute URL is a complete address of a resource on the web.
This completed address comprises of protocol used, server
name, path name and file name.
For example:
http:// www.tutorialspoint.com / Internet_technology /index.htm.
where:

http is the protocol;

tutorialspoint.com is the server name;

index.htm is the file name.
The protocol part tells the web browser how to handle the file.
Similarly we have some other protocols also that can be used
to create URL are:

FTP;

https;

Gopher;

Mailto;

News.
8.4.2
Relative URL
Relative URL is a partial address of a web page. Unlike
absolute URL, the protocol and server part are omitted from
relative URL.
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Relative URLs are used for internal links, i.e. to create links to
file that are part of same website as the Web Pages on which
you are placing the link.
For
example,
to
link
an
image
on
tutorialspoint.com/Internet_technology/Internet_referemce_mo
dels, we can use the relative URL which can take the form like:
/Internet_technologies/Internet-osi_model.jpg
8.5
Difference between Absolute and
Relative URL
Absolute URL
Relative URL
Used to link web pages on
different websites.
Used to link web pages within the
same website.
Difficult to manage.
Easy to Manage.
Changes when the server
name or directory name
changes.
Remains same even if we
change the server name or
directory name.
Take time to access.
Comparatively faster to access.
9
Domain Name System Architecture
The Domain name system comprises of Domain Names,
Domain Name Space and Name Server that have been
described below:
9.1
Domain Names
Domain Name is a symbolic string associated with an IP
address. There are several domain names available; some of
them are generic such as com, edu, gov, net, etc., while some
country level domain names such as au, in, za, us, etc.
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The following table shows the Generic Top-Level Domain
names:
Domain Name
Meaning
Com
Commercial business
Edu
Education
Gov
U.S. government agency
Int
International entity
Mil
U.S. military
Net
Networking organisation
Org
Non-profit organisation
The following table shows the Country top-level domain
names:
Domain Name
Meaning
au
Australia
in
India
cl
Chile
fr
France
us
United States
za
South Africa
uk
United Kingdom
jp
Japan
es
Spain
de
Germany
ca
Canada
ee
Estonia
hk
Hong Kong
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Domain Name Space
The domain name space refers a hierarchy in the Internet
naming structure. This hierarchy has multiple levels (from zero
to 127), with a root at the top. The following diagram shows the
domain name space hierarchy:
In the above diagram each sub-tree represents a domain.
Each domain can be partitioned into sub-domains and these
can be further partitioned and so on.
9.3
Name Server
Name server contains the DNS database. This database
comprises of various names and their corresponding IP
addresses. Since it is not possible for a single server to
maintain entire DNS database, therefore, the information is
distributed among many DNS servers.


9.4
Hierarchy of server is same as hierarchy of names;
The entire name space is divided into the zones
Zones
Zones are a collection of nodes (sub-domains) under the main
domain. The server maintains a database called zone file for
every zone.
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If the domain is not further divided into sub-domains then
domain and zone refers to the same thing.
The information about the nodes in the sub-domain is stored in
the servers at the lower levels however; the original server
keeps reference to these lower levels of servers.
9.4.1
Types of Name Servers
Following are the three categories of Name Servers that
manages the entire Domain Name System:
1.
Root Server
2.
Primary Server
3.
Secondary Server
Root Server
Root Server is the top level server which consists of the entire
DNS tree. It does not contain the information about domains,
but delegates the authority to the other server.
Primary Servers
Primary Server stores a file about its zone. It has authority to
create, maintain and update the zone file.
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Secondary Server
Secondary Server transfers complete information about a zone
from another server which may be primary or secondary
server. The secondary server does not have authority to create
or update a zone file.
10 DNS Working
DNS translates the domain name into IP address
automatically. The following steps will take you through the
steps included in domain resolution process:

When we type www.tutorialspoint.com into the browser,
it asks the local DNS Server for its IP address. Here the
local DNS is at ISP end;

When the local DNS does not find the IP address of
requested domain name, it forwards the request to the
root DNS server and again enquires about IP address of
it;

The root DNS server replies with delegation that “I do
not know the IP address of www.tutorialspoint.com, but
know the IP address of DNS Server”;

The local DNS server then asks the com DNS Server
the same question;

The com DNS Server replies the same that it does not
know the IP address of www.tutorialspont.com, but
knows the address of tutorialspoint.com;

Then the local DNS asks the tutorialspoint.com DNS
server the same question;

Then tutorialspoint.com DNS server replies with IP
address of www.tutorialspoint.com;

Now, the local DNS sends the IP address of
www.tutorialspoint.com to the computer that sends the
request.
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Chapter 4: Internet Collaboration
1
1.1
Internet Collaboration Overview
Online Chatting
Online chatting is a text-based communication between two or
more people over a network. In this, the text message is
delivered in real time and people get immediate response.
Talkomatic was the world first online chat system. It was
developed by Doug Brown and David R. Woolley in 1973.
1.1.1
Chat Etiquette
Chat etiquette defines rules that are supposed to be followed
while online chatting:

Avoid chat slang;

Try to spell all words correctly;

Do not write all the words in capital;

Do not send other chat users private messages without
asking them;

Abide by the rules created by those running the chat;

Use emoticons to let other person know your feelings
and expressions.
1.1.2
Web-based Chat Services
Following web sites offers browser based chat services:
Website
Description
Facebook
It was founded by Mark Zuckerberg with his
college roommates at Harvard university.
Facebook lets the user to create personal profile,
post a status and photos and receive notifications.
eBuddy
It is an instant messaging service. It supports
multiprotocol instant messaging clients.
Convore
It offers real time web-based chat system.
MeBeam
It offers video-based chat between the clients to
create video conferencing rooms for up to 16
people.
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Description
It offers PC-PC, PC-phone, Phone-to-PC, file
Yahoo!
transfer, webcam hosting, text messaging
Messenger
services, etc.
WhatsApp
It is an instant messaging service application
available on smart phones.
Gmail
It offers instant chatting, sending and receiving
mails and video calling services.
1.1.3
Instant Messaging (IM)
Instant messaging is a software utility that allows IM users to
communicate by sending text messages, files and images.
Some of the IMs also support voice and video calls.
Application Description
Nimbuzz
It is a native iPhone app. It supports voice and
video chats, file sharing and group chats with
panache.
eBuddy
eBuddy IM helps to have all your buddies from
multiple IM accounts in one single list.
Imo.in
It has capability to link all your IM accounts
together. You can log on to all of your IM
accounts by just logging into imo.in.
MeBeam
It offers video-based chat between the clients to
create video conferencing rooms for up to 16
people.
Yahoo!
Messenger
It offers PC-PC, PC-phone, Phone-to-PC, file
transfer, webcam hosting, text messaging
service, etc.
GoogleTalk
It is an IM by Google and one of the most widely
used.
Lync
Lync is an IM developed by Microsoft. It is widely
used in corporate sector for internal and external
communication as well.
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Internet Relay Chat (IRC)
Internet Relay Chat is a protocol developed by Oikarinen in
August 1988. It defines a set of rules for communication
between client and server by some communication mechanism
such as chat rooms, over the Internet.
IRC consists of separate networks of IRC servers and
machines. These allow IRC clients to connect to IRC. IRC
clients run a program client to connect to a server on one of
the IRC nets. After connecting to IRC server on IRC network,
users can join with one or more channels and converse over
there.
IRC Commands
Following commands are used while connected to an IRC
server. Almost of the below commands will work with most of
IRC clients and servers.
Command
Description
/away
(message)
Leaves a message let the others know why
you are gone.
/clear
Clears the text from current window.
/clearall
Clears all the text from all of the opened
windows.
/dcc chat
(username)
Opens a chat window with the username
that you specify.
/help
Brings up a list of all the commands or the
help window.
/ignore (on/of)
(username)
Allows you to ignore or not ignore a user.
/ignore (+/-)
(username)
Alternative to ignore or not ignore a user.
/join (#channel)
Joins a particular chat group.
/nick
(username)
Changes the username
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Command
Description
/part (channel)
Leaves specified channel.
/ping
(username)
Pings a specified user and it let you know
how far they are in seconds
/whowas
(username)
Shows information about specified user that
was in earlier.
/ping (channel)
Pings all users in specified channel.
1.2
Video Conferencing
Video conferencing or Video teleconferencing is a method of
communicating by two-way video and audio transmission with
help of telecommunication technologies.
1.3
Modes of Video Conferencing
1.3.1
Point-To-Point
This mode of conferencing connects two locations only.
1.3.2
Multi-Point
This mode of conferencing connects more than two locations
through Multi-point Control Unit (MCU).
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Video Sharing
Video sharing is an IP Multimedia System (IMS) service that
allows users to switch voice calls to unidirectional video
streaming session. The video streaming session can be
initiated by any of the parties. Moreover, the video source can
be the camera or the pre-recorded video clip.
2
2.1
Mailing List
Mailing List Overview
In order to send the same email to a group of people, an
electronic list is created which is known as Mailing List. It is the
list server which receives and distributes postings and
automatically manages subscriptions. Mailing list offers a
forum, where users from all over the globe can answer
questions and have them answered by others with shared
interests.
2.2
Types of Mailing List
Following are the various types of mailing lists:

Response List
It contains the group of people who have responded to
an offer in some way. These people are the customers
who have shown interest in specific product or service.

Compiled List
The compiled list is prepared by collecting information
from various sources such as surveys, telemarketing,
etc.
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
Announcements
These lists are created for sending out coupons, new
product announcements and other offers to the
customers.

Discussion List
This list is created for sharing views on a specific topic
such as computer, environment, health, education, etc.
2.3
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How does a Mailing List Work?
Before joining a mailing list, it is mandatory to subscribe to it.
Once you are subscribed, your message will be sent to all the
persons who have subscribed to the list. Similarly if any
subscriber posts a message, then it will be received by all
subscribers of the list.
2.4
Finding a Mailing List
There are a number of websites are available to maintain
database of publically accessible mailing list. Some of these
are:

http://tile.net./lists;

http://lists.com;

http://topica.com;

http://isoft.com/lists/list-q.html.
Mailing lists can also be found using Google website. In
Google, move to directory and the follow: Computers > Internet
>Mailing List > Directories.
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Subscribing to a Mailing List
To subscribe to a list, you need to send an email message to
the administrative address mailing list containing one or more
commands. For example, if you want to subscribe to Harry
Potter list in gurus.com where name of the list server is
Majordomo,
then
you
have
to
send
email
to
majordom@gurus.com containing the text, Subscribe harry
potter in its body.
After sending the email, you will receive a confirmation email
for your subscription. This email will include list of commands
that will help you to perform various operations such as
unsubscribing, receiving acknowledgement and find out what
list you are subscribed to.
There are many list servers available, each having its own
commands for subscribing to the list. Some of them are
described in the following table:
List
Server
Command
Example
LISTSERV
subscribe listname
yourname
subscribe commdhtml
rahul
Majordomo subscribe listname
subscribe commdhtml
subscribe listname
yourname
subscribe commdhtml
rahul
ListProc
3
3.1
Usenet Newsgroup
Usenet (USEr NETwork)
Like mailing lists, Usenet is also a way of sharing information.
It was started by Tom Truscott and Jim Ellis in 1979. Initially it
was limited to two sites, but today there are thousands of
Usenet sites involving millions of people. Usenet is a kind of
discussion group where people can share views on topic of
their interest. The article posted to a newsgroup becomes
available to all readers of the newsgroup.
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Newsgroup Classification
There exist a number of newsgroups distributed all around the
world. These are identified using a hierarchical naming system
in which each newsgroup is assigned a unique name that
consists of alphabetic strings separated by periods.
The leftmost portion of the name represents the top-level
category of the newsgroup followed by a sub-topic. The subtopic can further be sub-divided and sub-divided even further
(if needed).
For example, the newsgroup comp.lang.C++ contains
discussion on C++language. The leftmost part comp classifies
the newsgroup as one that contains discussion of computer
related topics. The second part identifies one of the subtopic
lang that related to computer languages. The third part
identifies one of the computer languages, in this case C++.
The following table shows the top-level hierarchies of Usenet
Newsgroup:
Comp.*
Computer related topics
including computer
Comp.lang.java.beans
hardware, software,
Comp.database.oracle
languages, etc.
News.*
Newsgroup and Usenet
topics.
Rec.*
Artistic activities,
hobbies or recreational
Rec.arts.animation
activities such as books,
movies, etc.
News.software.nntp
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Sci.*
Scientific topics
Sci.bio.botany
Soc.*
Social issues and
various culture.
Soc.culture.india
Talk.*
Conventional subjects
such as religion,
politics, etc.
Soc.politics.india
Humanities.*
Art, literature,
philosophy and culture.
Humanities.classics
Misc.*
Miscellaneous topics,
i.e. issues that may not
fit into other categories.
Misc.answers
Misc.books.technical
3.3
Working of Usenet Newsgroup
When a newsreader such as outlook express connects to a
news server, it downloads all the new messages posted in the
subscribed newsgroup. We can either reply to a message after
reading or post a news article to the news server. The article
posted to a news server is appended to the file maintained for
that newsgroup. Then the news server shares article with other
news servers that are connected to it.
Then each news server compares if both carry the same
newsgroup. If yes, then by comparing the files it checks that if
there are any new articles in the file, if so they are appended to
the file. The updated file of the news servers is then sent to
other news servers connected to it. This process is continues
until all of the news servers have updated information.
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Reading Articles
If users want to read an article, users have to connect to the
news server using the newsreader. The newsreader will then
display a list of newsgroups available on the news server
where users can subscribe to any of the news groups. After
subscription the newsreader will automatically download
articles from the newsgroup.
After reading the article users can either post a reply to the
newsgroup or reply to the sender by email. The newsreader
saves information about the subscribed newsgroups and
articles read by the user in each group.
3.3.2
Posting an Article
In order to send a new article to a newsgroup, users first need
to compose an article and specify the names of the newsgroup
to whom he/ she wants to send. An article can be sent to one
or more newsgroups at a time provided all the newsgroups are
on the same news server.
It is also possible to cancel the article that you have posted,
but if someone has downloaded an article before cancellation
then that person will be able to read the article.
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Replying an Article
After reading the article users can either post a reply to
newsgroup or reply to the sender by email. There are two
options available: Reply and Reply group. Using Reply, the
reply mail will be sent to the author of the article while Reply
group will send a reply to whole of the newsgroup.
3.3.4
Cancelling an Article
To cancel an article after it is sent, select the message and
click Message > Cancel message: it will cancel the message
from the news server. But if someone has downloaded an
article before cancellation then that person will be able to read
the article.
3.4
Usenet Netiquette
While posting an article on a newsgroup, one should follow
some rules of netiquette as listed below:

Spend some time in understanding a newsgroup when
you join it for first time;

Articles posted by you should be easy to read, concise
and grammatically correct;

Information should be relevant to the article title;

Do not post the same article to multiple newsgroups;

Avoid providing your business email address while
subscribing to a newsgroup as may be used by
spammers;

Avoid using capital letters as someone may interpret as
shouting;

Preferably, use plain text wherever possible in your
article.
3.5
Mailing list vs. Newsgroup
Mailing List Newsgroup
Messages are delivered to
individual mailboxes of
1.
subscribed member of
group.
Messages are not posted to
individual mailboxes, but
can be viewed by anyone
who has subscribed to that
newsgroup.
Working with a mailing list is
easier than newsgroup. It is
2.
easy to compose and
receive emails.
Working with a particular
newsgroup requires proper
knowledge of that
newsgroup.
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Mailing List Newsgroup
In order to send or receive
3. mails, you require an email
program.
It requires a newsgroup
reader.
4.
Messages are delivered to a
certain group of people.
Messages are available to
public.
5.
Mailing lists do not support
threaded discussion.
Newsgroups support
threaded discussion.
Messages delivered to listed
6. subscribers cannot be
cancelled.
4
4.1
Article posted on a
newsgroup can be
cancelled.
Online Education
Online Training
Online Training is a form of distance learning in which
educational information is delivered through the Internet. There
are many online applications. These applications vary from
simple downloadable content to structured programs.
4.1.1
Benefits
Online Training has proved to be very effective in corporate
world. The benefits of Online Training are described below:

It is cost effective and saves time;

It is available 24/7 anywhere;

It is easy to track progress of the course;

It offers user-friendly and interactive interface.
4.2
Online Certification
It is also possible to do online certification on specialised
courses which add value to your qualification. Many
companies offer online certification on a number of
technologies.
There are three types of online certification as listed below:

Corporate;

Product-specific;

Profession-wide.
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

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Corporate certifications are made by small organisations
for internal purposes;
Product-specific certifications target developing and
recognising adeptness with regard to particular product;
Profession-wide certification aims at recognising
expertise in particular profession.
Online Seminar
Online seminar is the one which is conducted over the Internet.
It is a live seminar and allows the attendees to ask questions
via Q&A panel onscreen. Online seminars just require a
computer with Internet connection, headphones, speakers and
authorisation to attend it.
4.3.1
Benefits
Online Seminar has proved to be very effective in corporate
and Academic world. The benefits of Online Seminar are
described below:

Online seminars are short, sharp and to the point;

They always tend to deal with a specific subject in detail;

Since the user participates online, therefore, manuals
are provided via. Pdf;

Online seminars are cost effective and convenient.
4.4
Webinar
Webinar is a web-based seminar or workshop in which
presentation is delivered over the web using conferencing
software. The audio part of webinar is delivered through
teleconferencing.
4.5
Conferencing
Online conferencing is also a kind of online seminar in which
two or more people are involved. It is also performed over the
Internet. It allows the business persons to do meeting online.
4.5.1
Benefits
Online Webinar has proved to be very effective in corporate
and Academic world. The benefits of Online Webinar are
described below:

It is cheaper and convenient;

It can be accessed 24/7 anywhere;
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

It allows high level of participation;
There is permanent record of proceedings.
5
Social Networking
5.1
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Introduction
Social Networking refers to grouping of individuals and
organisations together via some medium, in order to share
thoughts, interests and activities.
There are several web-based social network services are
available such as Facebook®, Twitter®, LinkedIn® and
Google+®, etc., which offer easy to use and interactive
interfaces to connect with people with in the same country and
overseas as well. There are also several mobile-based social
networking services in the form of apps such as WhatsApp®,
etc.
5.2
Available Social Networking Services
The following table describes some of the famous social
networking services provided over web and mobile:
Service Description
1.
Facebook®
Allows users to share text, photos and video, etc. It also
offers interesting online games.
2.
Google+®
It is pronounced as Google Plus. It is owned and operated
by Google.
3.
Twitter®
Twitter allows the user to send and reply to messages in
form of tweets. These tweets are the small messages,
generally include 140+ characters.
4.
Faceparty®
Faceparty is a UK-based social networking site. It allows
the users to create profiles and interact with each other
using forums messages.
5.
Linkedin®
Linkedin is a business and professional networking site.
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Service Description
6.
Flickr®
Flickr offers image hosting and video hosting.
7.
Ibibo®
Ibibo is a talent-based social networking site. It allows the
users to promote oneself and also discover new talent.
8.
WhatsApp®
It is a mobile-based messaging app. It allows to send text,
video and audio messages
9.
Line®
It is same as WhatsApp. Allows users to make free calls
and messages.
Hike®
10. It is also mobile-based messenger which allows users to
send messages and exciting emoticons.
5.3
Where Social Networking Helps
Following are the areas where social networking has become
most popular:

Online Marketing
Website like Facebook® allows us to create a page for a
specific product, community or firm and promoting over
the web.

Online Jobs
Website like LinkedIn® allows us to create connections
with professionals and helps to find the suitable job
based on one’s specific skills set.

Online News
On social networking sites, people also post daily news
which helps us to keep us updated.

Chatting
Social networking allows us to keep in contact with
friends and family. We can communicate with them via
messages.

Share files
One can share pictures, audio and video using social
networking sites.
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Chapter 5: Internet of Things
1
Internet of Things (IoT) — Overview
IoT systems allow users to achieve deeper automation,
analysis and integration within a system. They improve the
reach of these areas and their accuracy. IoT utilises existing
and emerging technology for sensing, networking and robotics.
IoT exploits recent advances in software, falling hardware
prices and modern attitudes towards technology. Its new and
advanced elements bring major changes in the delivery of
products, goods and services; and the social, economic and
political impact of those changes.
1.1
IoT — Key Features
The most important features of IoT include artificial
intelligence, connectivity, sensors, active engagement and
small device use. A brief review of these features is given
below:

AI — IoT essentially makes virtually anything “smart”,
meaning it enhances every aspect of life with the power
of data collection, artificial intelligence algorithms and
networks. This can mean something as simple as
enhancing your refrigerator and cabinets to detect when
milk and your favourite cereal run low and to then place
an order with your preferred grocer;

Connectivity — New enabling technologies for
networking, and specifically IoT networking, mean
networks are no longer exclusively tied to major
providers. Networks can exist on a much smaller and
cheaper scale while still being practical. IoT creates
these small networks between its system devices;

Sensors — IoT loses its distinction without sensors.
They act as defining instruments which transform IoT
from a standard passive network of devices into an
active system capable of real-world integration;

Active Engagement — Much of today's interaction with
connected technology happens through passive
engagement. IoT introduces a new paradigm for active
content, product or service engagement;

Small Devices — Devices, as predicted, have become
smaller, cheaper and more powerful over time. IoT
exploits purpose-built small devices to deliver its
precision, scalability and versatility.
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IoT — Advantages
The advantages of IoT span across every area of lifestyle and
business. Here is a list of some of the advantages that IoT has
to offer:

Improved Customer Engagement — Current analytics
suffer from blind-spots and significant flaws in accuracy
and, as noted, engagement remains passive. IoT
completely transforms this to achieve richer and more
effective engagement with audiences;

Technology Optimisation — The same technologies and
data which improve the customer experience also
improve device use and aid in more potent
improvements to technology. IoT unlocks a world of
critical functional and field data;

Reduced Waste — IoT makes areas of improvement
clear. Current analytics give us superficial insight, but
IoT provides real-world information leading to more
effective management of resources;

Enhanced Data Collection — Modern data collection
suffers from its limitations and its design for passive use.
IoT breaks it out of those spaces and places it exactly
where humans really want to go; to analyse our world. It
allows an accurate picture of everything.
1.3
IoT — Disadvantages
Though IoT delivers an impressive set of benefits, it also
presents a significant set of challenges. Here is a list of some
its major issues:

Security — IoT creates an ecosystem of constantly
connected devices communicating over networks. The
system offers little control despite any security
measures. This leaves users exposed to various kinds
of attackers;

Privacy — The sophistication of IoT provides substantial
personal data in extreme detail without the user's active
participation;

Complexity — Some find IoT systems complicated in
terms of design, deployment and maintenance given
their use of multiple technologies and a large set of new
enabling technologies;

Flexibility — Many are concerned about the flexibility of
an IoT system to integrate easily with another. They
worry about finding themselves with several conflicting
or locked systems;
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
Compliance — IoT, like any other technology in the
realm of business, must comply with regulations. Its
complexity makes the issue of compliance seem
incredibly challenging when many consider standard
software compliance a battle.
2
Internet of Things — Hardware
The hardware utilised in IoT systems includes devices for a
remote dashboard, devices for control, servers, a routing or
bridge device and sensors. These devices manage key tasks
and functions such as system activation, action specifications,
security, communication and detection to support-specific
goals and actions.
2.1
IoT — Sensors
The most important hardware in IoT might be its sensors.
These devices consist of energy modules, power management
modules, RF modules and sensing modules. RF modules
manage communications through their signal processing; WiFi,
ZigBee, Bluetooth, radio transceiver, duplexer and BAW.
The sensing module manages sensing through assorted active
and passive measurement devices. Here is a list of some of
the measurement devices used in IoT:
Devices
1.
accelerometers
temperature sensors
2.
magnetometers
proximity sensors
3.
gyroscopes
image sensors
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Devices
4.
Acoustic sensors
light sensors
5.
pressure sensors
gas RFID sensors
6.
humidity sensors
micro flow sensors
2.2
Wearable Electronics
Wearable electronic devices are small devices worn on the
head, neck, arms, torso and feet.
Smartwatches not only help us stay connected, but as a part of
an IoT system, they allow access needed for improved
productivity. Current smart wearable devices include:

Head — Helmets, glasses;

Neck — Jewellery, collars;

Arm — Watches, wristbands, rings;

Torso — Clothing, backpacks;

Feet — Socks, shoes.
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Smart glasses help us enjoy more of the media and services
we value and, when part of an IoT system, they allow a new
approach to productivity.
2.3
Standard Devices
The desktop, tablet and cellphone remain integral parts of IoT
as the command centre and remotes.



The desktop provides the user with the highest level of
control over the system and its settings;
The tablet provides access to the key features of the
system in a way resembling the desktop and also acts
as a remote;
The cellphone allows some essential settings
modification and also provides remote functionality.
Other key connected devices include standard network
devices like routers and switches.
3
Internet of Things — Software
IoT software addresses its key areas of networking and action
through platforms, embedded systems, partner systems and
middleware. These individual and master applications are
responsible for data collection, device integration, real-time
analytics and application and process extension within the IoT
network. They exploit integration with critical business systems
(e.g. ordering systems, robotics, scheduling and more) in the
execution of related tasks.
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Data Collection
This software manages sensing, measurements, light data
filtering, light data security and aggregation of data. It uses
certain protocols to aid sensors in connecting with real-time,
machine-to-machine networks. Then it collects data from
multiple devices and distributes it in accordance with settings.
It also works in reverse by distributing data over devices. The
system eventually transmits all collected data to a central
server.
3.2
Device Integration
Software
supporting
integration
binds
(dependent
relationships) all system devices to create the body of the IoT
system. It ensures the necessary cooperation and stable
networking between devices. These applications are the
defining software technology of the IoT network because
without them, it is not an IoT system. They manage the various
applications, protocols and limitations of each device to allow
communication.
3.3
Real-Time Analytics
These applications take data or input from various devices and
convert it into viable actions or clear patterns for human
analysis. They analyse information based on various settings
and designs in order to perform automation-related tasks or
provide the data required by industry.
3.4
Application and Process Extension
These applications extend the reach of existing systems and
software to allow a wider, more effective system. They
integrate predefined devices for specific purposes such as
allowing certain mobile devices or engineering instruments
access. It supports improved productivity and more accurate
data collection.
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Internet of Things — Technology
and Protocols
IoT primarily exploits standard protocols and networking
technologies. However, the major enabling technologies and
protocols of IoT are RFID, NFC, low-energy Bluetooth, lowenergy wireless, low-energy radio protocols, LTE-A and WiFiDirect. These technologies support the specific networking
functionality needed in an IoT system in contrast to a standard
uniform network of common systems.
4.1
NFC and RFID
RFID (radio-frequency identification) and NFC (near-field
communication) provide simple, low-energy and versatile
options for identity and access tokens, connection
bootstrapping and payments.


4.2
RFID technology employs two-way radio transmitterreceivers to identify and track tags associated with
objects;
NFC consists of communication protocols for electronic
devices, typically a mobile device and a standard
device.
Low-Energy Bluetooth
This technology supports the low-power, long-use need of IoT
function while exploiting a standard technology with native
support across systems.
4.3
Low-Energy Wireless
This technology replaces the most power hungry aspect of an
IoT system. Though sensors and other elements can power
down over long periods, communication links (i.e. wireless)
must remain in listening mode. Low-energy wireless not only
reduces consumption, but also extends the life of the device
through less use.
4.4
Radio Protocols
ZigBee, Z-Wave and Thread are radio protocols for creating
low-rate private area networks. These technologies are lowpower, but offer high throughput unlike many similar options.
This increases the power of small local device networks
without the typical costs.
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LTE-A
LTE-A or LTE Advanced, delivers an important upgrade to LTE
technology by increasing not only its coverage, but also
reducing its latency and raising its throughput. It gives IoT a
tremendous power through expanding its range, with its most
significant applications being vehicle, UAV and similar
communication.
4.6
WiFi-Direct
WiFi-Direct eliminates the need for an access point. It allows
P2P (peer-to-peer) connections with the speed of WiFi, but
with lower latency. WiFi-Direct eliminates an element of a
network that often bogs it down and it does not compromise on
speed or throughput.
5
Internet of Things — Common Uses
IoT has applications across all industries and markets. It spans
user groups from those who want to reduce energy use in their
home to large organisations that want to streamline their
operations. It proves not just useful, but nearly critical in many
industries as technology advances and we move towards the
advanced automation imagined in the distant future.
5.1
Engineering, Industry and Infrastructure
Applications of IoT in these areas include improving
production, marketing, service delivery and safety. IoT
provides a strong means of monitoring various processes and
real transparency creates greater visibility for improvement
opportunities. The deep level of control afforded by IoT allows
rapid and more action on those opportunities, which include
events like obvious customer needs, non-conforming product,
malfunctions in equipment, problems in the distribution network
and more.
5.1.1
Example
Joan runs a manufacturing facility that makes shields for
manufacturing equipment. When regulations change for the
composition and function of the shields, the new appropriate
requirements are automatically programmed in production
robotics and engineers are alerted about their approval of the
changes.
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Government and Safety
IoT applied to government and safety allows improved law
enforcement, defence, city planning and economic
management. The technology fills in the current gaps, corrects
many current flaws and expands the reach of these efforts.
For example, IoT can help city planners have a clearer view of
the impact of their design and governments have a better idea
of the local economy.
5.2.1
Example
Joan lives in a small city. She has heard about a recent spike
in crime in her area and worries about coming home late at
night. Local law enforcement has been alerted about the new
“hot” zone through system flags and they have increase their
presence. Area monitoring devices have detected suspicious
behaviour and law enforcement has investigated these leads
to prevent crimes.
5.3
Home and Office
In our daily lives, IoT provides a personalised experience from
the home to the office to the organisations we frequently do
business with. This improves our overall satisfaction, enhances
productivity and improves our health and safety.
For example, IoT can help us customise our office space to
optimise our work.
5.3.1
Example
Joan works in advertising. She enters her office and it
recognises her face. It adjusts the lighting and temperature to
her preference. It turns on her devices and opens applications
to her last working points. Her office door detected and
recognised a colleague visiting her office multiple times before
she arrived. Joan’s system opens this visitor’s messages
automatically.
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Health and Medicine
IoT pushes us towards our imagined future of medicine which
exploits a highly integrated network of sophisticated medical
devices. Today, IoT can dramatically enhance medical
research, devices, care and emergency care. The integration
of all elements provides more accuracy, more attention to
detail, faster reactions to events and constant improvement
while reducing the typical overhead of medical research and
organisations.
5.4.1
Example
Joan is a nurse in an emergency room. A call has come in for
a man wounded in an altercation. The system recognised the
patient and pulls his records. On the scene, paramedics’
equipment captures critical information automatically sent to
the receiving parties at the hospital. The system analyses the
new data and current records to deliver a guiding solution. The
status of the patient is updated every second in the system
during his transport. The system prompts Joan to approve
system actions for medicine distribution and medical
equipment preparation.
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Chapter 6: Data Communication and
Computer Network
A system of interconnected computers and computerised
peripherals, such as printers, are called computer networks.
This interconnection among computers facilitates information
sharing among them. Computers may connect to each other
by either wired or wireless media.
1
Classification of Computer
Networks
Computer networks are classified based on various factors.
They include:

Geographical span;

Inter-connectivity;

Administration;

Architecture.
1.1
Geographical Span
Geographically a network can be seen in one of the following
categories:

It may be spanned across your table, among Bluetooth
enabled devices, ranging not more than few meters;

It may be spanned across a whole building, including
intermediate devices to connect all floors;

It may be spanned across a whole city;

It may be spanned across multiple cities or provinces;

It may be one network covering whole world.
1.2
Inter-Connectivity
Components of a network can be connected to each other
differently in some fashion. By connectedness we mean either
logically, physically or both ways.

Every single device can be connected to every other
device on network, making the network mesh;

All devices can be connected to a single medium, but
geographically disconnected, creating a bus like
structure;

Each device is connected to its left and right peers only,
creating linear structure;

All devices connected together with a single device,
creating star like structure;
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All devices connected arbitrarily using all previous ways
to connect each other, resulting in a hybrid structure.
Administration
From an administrator’s point of view, a network can be private
network which belongs to a single autonomous system and
cannot be accessed outside its physical or logical domain. A
network can be public which is accessed by all.
1.4




2
2.1
Network Architecture
Computer networks can be discriminated into various
types such as Client-Server, peer-to-peer or hybrid,
depending upon its architecture;
There can be one or more systems acting as Server.
Others being Client, requests the Server to serve
requests. Server takes and processes request on behalf
of Clients;
Two systems can be connected: Point-to-Point or in
back-to-back fashion. They both reside at the same level
and called peers;
There can be hybrid network which involves network
architecture of both the above types.
Computer Network Devices — Hub,
Switch, Router, Bridges
Network Applications
Computer systems and peripherals are connected to form a
network. They provide numerous advantages:

Resource sharing such as printers and storage devices;

Exchange of information by means of emails and FTP;

Information sharing by using the web or Internet;

Interaction with other users using dynamic web pages;

IP phones;

Video conferences;

Parallel computing;

Instant messaging.
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Computer Network Types
Generally, networks are distinguished based on their
geographical span. A network can be as small as distance
between your mobile phone and its Bluetooth headphone and
as large as the Internet itself, covering the whole geographical
world.
3.1
Personal Area Network
A Personal Area Network (PAN) is the smallest network, which
is very personal to a user. This may include Bluetooth enabled
devices or infra-red enabled devices. PAN has connectivity
range up to 10 meters. PAN may include wireless computer
keyboards and mouse, Bluetooth enabled headphones,
wireless printers and TV remotes.
For example, Piconet is Bluetooth-enabled Personal Area
Network which may contain up to eight devices connected
together in a master-slave fashion.
3.2
Local Area Network
A computer network spanned inside a building and operated
under single administrative system is generally termed as
Local Area Network (LAN). Usually, LAN covers an
organisation’s offices, schools, colleges or universities. The
number of systems connected in LAN may vary from as little
as two to as much as 16 million.
LAN provides a useful way of sharing the resources between
end users. The resources such as printers, file servers,
scanners and Internet are easily sharable among computers.
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LANs are composed of inexpensive networking and routing
equipment. It may contain local servers serving file storage
and other locally shared applications. It mostly operates on
private IP addresses and does not involve heavy routing. LAN
works under its own local domain and controlled centrally.
LAN uses either Ethernet or Token-ring technology. Ethernet is
most widely employed LAN technology and uses Star
topology, while Token-ring is rarely seen. LAN can be wired,
wireless, or in both forms at once.
3.3
Metropolitan Area Network
The Metropolitan Area Network (MAN) generally expands
throughout a city such as cable TV network. It can be in the
form of Ethernet, Token-ring, ATM or Fiber Distributed Data
Interface (FDDI).
Metro Ethernet is a service which is provided by ISPs. This
service enables its users to expand their Local Area Networks.
For example, MAN can help an organisation to connect all of
its offices in a city.
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The backbone of MAN is high-capacity and high-speed fiber
optics. MAN works in between Local Area Network and Wide
Area Network. MAN provides uplink for LANs to WANs or
Internet.
3.4
Wide Area Network
As the name suggests, the Wide Area Network (WAN) covers
a wide area which may span across provinces and even a
whole country. Generally, telecommunication networks are
Wide Area Network. These networks provide connectivity to
MANs and LANs. Since they are equipped with very high
speed backbone, WANs use very expensive network
equipment.
WAN may use advanced technologies such as Asynchronous
Transfer Mode (ATM), Frame Relay and Synchronous Optical
Network (SONET). WAN may be managed by multiple
administrations.
3.5
Internetwork
A network of networks is called an Internetwork or simply the
Internet. It is the largest network in existence on this planet.
The Internet hugely connects all WANs and it can have
connection to LANs and Home networks. Internet uses TCP/IP
protocol suite and uses IP as its addressing protocol. Present
day, Internet is widely implemented using IPv4. Because of
shortage of address spaces, it is gradually migrating from IPv4
to IPv6.
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Internet enables its users to share and access enormous
amounts of information worldwide. It uses WWW, FTP, email
services, audio and video streaming, etc. At a huge level,
Internet works on Client-Server model.
Internet uses very high speed backbone of fiber optics. To
inter-connect various continents, fibers are laid under sea
known to us as submarine communication cable.
Internet is widely deployed on World Wide Web services using
HTML linked pages and is accessible by client software known
as Web Browsers. When a user requests a page, using some
web browser located on some Web Server anywhere in the
world, the Web Server responds with the proper HTML page.
The communication delay is very low.
The Internet serves many proposes and is involved in many
aspects of life. Some of them are:

Web sites;

Email;

Instant Messaging;

Blogging;

Social Media;

Marketing;

Networking;

Resource Sharing;

Audio and Video Streaming.
4
Network LAN Technologies
Let us go through various LAN technologies in brief:
4.1
Ethernet
Ethernet is a widely deployed LAN technology. This technology
was invented by Bob Metcalfe and D.R. Boggs in the year
1970. It was standardised in IEEE 802.3 in 1980.
Ethernet shares media. Networks, which use shared media,
have high probability of data collision. Ethernet uses Carrier
Sense Multi Access/ Collision Detection (CSMA/CD)
technology to detect collisions. On the occurrence of collision
in Ethernet, all its hosts roll back, wait for some random
amount of time and then re-transmit the data.
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Ethernet connector is a network interface card equipped with
48-bits MAC address. This helps other Ethernet devices to
identify and communicate with remote devices in Ethernet.
Traditional Ethernet uses 10BASE-T specifications. The
number 10 depicts 10MBPS speed, BASE stands for
baseband and T stands for Thick Ethernet. 10BASE-T
Ethernet provides a transmission speed up to 10MBPS and
uses coaxial cable or Cat-5 twisted pair cable with RJ-45
connector. Ethernet follows star topology with a segment
length of up to 100 meters. All devices are connected to a hub/
switch in a star fashion.
4.2
Fast-Ethernet
To encompass need of fast emerging software and hardware
technologies, Ethernet extends itself as Fast-Ethernet. It can
run on UTP, Optical Fiber and wirelessly too. It can provide
speed up to 100 MBPS. This standard is named as 100BASET in IEEE 803.2 using Cat-5 twisted pair cable. It uses the
CSMA/CD technique for wired media sharing among the
Ethernet hosts and CSMA/CA (CA stands for Collision
Avoidance) technique for wireless Ethernet LAN.
Fast Ethernet on fiber is defined under 100BASE-FX standard
which provides speed up to 100 MBPS on fiber. Ethernet over
fiber can be extended up to 100 meters in half-duplex mode
and can reach maximum of 2 000 meters in full-duplex over
multimode fibers.
4.3
Giga-Ethernet
After being introduced in 1995, Fast-Ethernet could enjoy its
high speed status only for three years until Giga-Ethernet was
introduced. Giga-Ethernet provides speed up to 1 000
mbits/seconds. IEEE802.3ab standardised Giga-Ethernet over
UTP using Cat-5, Cat-5e and Cat-6 cables. IEEE802.3ah
defines Giga-Ethernet over Fiber.
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Virtual LAN
LAN uses Ethernet which in turn works on shared media.
Shared media in Ethernet create one single Broadcast domain
and one single Collision domain. The introduction of switches
to Ethernet has removed single collision domain issues and
each device connected to a switch works in its separate
collision domain. But even Switches cannot divide a network
into separate Broadcast domains.
Virtual LAN is a solution to divide a single Broadcast domain
into multiple Broadcast domains. Hosts in one VLAN cannot
speak to a host in another. By default, all hosts are placed into
the same VLAN.
In this diagram, different VLANs are depicted in different colour
codes. Hosts in one VLAN, even if connected on the same
Switch, cannot see or speak to other hosts in different VLANs.
VLAN is Layer-2 technology which works closely on Ethernet.
to route packets between two different VLANs. A Layer-3
device such as Router is required.
5
Computer Network Topologies
A Network Topology is the arrangement with which computer
systems or network devices are connected to each other.
Topologies may define both physical and logical aspect of the
network. Both logical and physical topologies could be the
same or different in a same network.
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Point-to-Point
Point-to-point networks contain exactly two hosts such as
computer, switches or routers and servers connected back to
back using a single piece of cable. Often, the receiving end of
one host is connected to sending end of the other and viceversa.
If the hosts are connected point-to-point logically, then they
may have multiple intermediate devices. But the end hosts are
unaware of underlying network and see each other as if they
are connected directly.
5.2
Bus Topology
In case of Bus topology, all devices share single
communication line or cable. Bus topology may have a
problem while multiple hosts sending data at the same time.
Therefore, Bus topology uses either CSMA/CD technology or
recognises one host as Bus Master to solve the issue. It is one
of the simple forms of networking where a failure of a device
does not affect the other devices. But failure of the shared
communication line can make all other devices stop
functioning.
Both ends of the shared channel have line terminator. The
data is sent in only one direction and as soon as it reaches the
extreme end, the terminator removes the data from the line.
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Star Topology
All hosts in Star topology are connected to a central device,
known as hub device, using a point-to-point connection. That
is, there exists a point-to-point connection between hosts and
the hub. The hub device can be any of the following:

Layer-1 device such as hub or repeater;

Layer-2 device such as switch or bridge;

Layer-3 device such as router or gateway.
As in Bus topology, hubs act as a single point of failure. If a
hub fails, connectivity of all hosts to all other hosts fails. Every
communication between hosts, takes place through only the
hub. Star topology is not expensive as to connect one more
host, only one cable is required and configuration is simple.
5.4
Ring Topology
In ring topology, each host machine connects to exactly two
other machines, creating a circular network structure. When
one host tries to communicate or send message to a host
which is not adjacent to it, the data travels through all
intermediate hosts. To connect one more host in the existing
structure, the administrator may need only one more extra
cable.
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Failure of any host results in failure of the whole ring. Thus,
every connection in the ring is a point of failure. There are
methods which employ one more backup ring.
5.5
Mesh Topology
In this type of topology, a host is connected to one or multiple
hosts. This topology has hosts in point-to-point connection with
every other host or may also have hosts which are in point-topoint connection to few hosts only.
Hosts in Mesh topology also work as relay for other hosts
which do not have direct point-to-point links. Mesh technology
comes into two types:

Full Mesh: All hosts have a point-to-point connection to
every other host in the network. Thus for every new host
n(n-1)/2 connections are required. It provides the most
reliable network structure among all network topologies;
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Partially Mesh: Not all hosts have point-to-point
connection to every other host. Hosts connect to each
other in some arbitrarily fashion. This topology exists
where we need to provide reliability to some hosts out of
all.
Tree Topology
Also known as Hierarchical Topology, this is the most common
form of network topology in use presently. This topology
imitates as extended Star topology and inherits properties of
bus topology.
This topology divides the network in to multiple levels/ layers of
network. Mainly in LANs, a network is bifurcated into three
types of network devices. The lowermost is the access-layer
where computers are attached. The middle layer is known as
the distribution layer, which works as mediator between upper
layer and lower layer. The highest layer is known as the core
layer and is the central point of the network, i.e. root of the tree
from which all nodes fork.
All neighbouring hosts have point-to-point connections
between them. Similar to the Bus topology, if the root goes
down, then the entire network suffers even though it is not the
single point of failure. Every connection serves as a point of
failure, failing of which divides the network into unreachable
segment.
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Daisy Chain
This topology connects all the hosts in a linear fashion. Similar
to Ring topology, all hosts are connected to two hosts only,
except the end hosts, which means that if the end hosts in
daisy chain are connected then it represents Ring topology.
Each link in daisy chain topology represents single point of
failure. Every link failure splits the network into two segments.
Every intermediate host works as relay for its immediate hosts.
5.8
Hybrid Topology
A network structure whose design contains more than one
topology is said to be hybrid topology. Hybrid topology inherits
merits and demerits of all the incorporating topologies.
The above picture represents an arbitrarily hybrid topology.
The combining topologies may contain attributes of Star, Ring,
Bus and Daisy-chain topologies. Most WANs are connected by
means of Dual-Ring topology and networks connected to them
are mostly Star topology networks. Internet is the best example
of largest Hybrid topology.
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Chapter 7: Computer Network Security
1
Introduction
During initial days of Internet, its use was limited to military and
universities for research and development purpose. Later
when all networks merged together and formed the Internet,
the data used to travel through public transit network. Common
people may send the data that can be highly sensitive such as
their bank credentials, username and passwords, personal
documents, online shopping details or confidential documents.
All security threats are intentional, i.e. they occur only if
intentionally triggered. Security threats can be divided into the
following categories:

Interruption
Interruption is a security threat in which availability of
resources is attacked. For example, a user is unable to
access its web-server or the web-server is hijacked.

Privacy-Breach
In this threat, the privacy of a user is compromised.
Someone, who is not the authorised person, is accessing
or intercepting data sent or received by the original
authenticated user.

Integrity
This type of threat includes any alteration or modification
in the original context of communication. The attacker
intercepts and receives the data sent by the sender and
the attacker then either modifies or generates false data
and sends to the receiver. The receiver receives the data
assuming that it is being sent by the original sender.

Authenticity
This threat occurs when an attacker or a security
violator, poses as a genuine person and accesses the
resources or communicates with other genuine users.
No technique in the present world can provide 100% security.
But steps can be taken to secure data while it travels in an
unsecured network or Internet. The most widely used
technique is Cryptography.
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Cryptography
Cryptography is a technique to encrypt the plain-text data
which makes it difficult to understand and interpret. There are
several cryptographic algorithms available in the present day
as described below:

Secret Key;

Public Key;

Message Digest.
2.1
Secret Key Encryption
Both sender and receiver have one secret key. This secret key
is used to encrypt the data at sender’s end. After the data is
encrypted, it is sent on the public domain to the receiver.
Because the receiver knows and has the Secret Key, the
encrypted data packets can easily be decrypted.
Example of secret key encryption is Data Encryption Standard
(DES). In Secret Key encryption, it is required to have a
separate key for each host on the network making it difficult to
manage.
2.2
Public Key Encryption
In this encryption system, every user has his/ her own Secret
Key and it is not in the shared domain. The secret key is never
revealed on public domain. Along with secret key, every user
has his/ her own, but public key. The public key is always
made public and is used by senders to encrypt the data. When
the user receives the encrypted data, he/ she can easily
decrypt it by using his/ her own Secret Key.
Example of public key encryption is Rivest-Shamir-Adleman
(RSA).
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Message Digest
In this method, actual data is not sent instead a hash value is
calculated and sent. The other end user, computes his/ her
own hash value and compares it with the one just received. If
both hash values are matched, then it is accepted otherwise
rejected.
Example of Message Digest is MD5 hashing. It is mostly used
in authentication where a user password is cross checked with
the one saved on the server.
3
Internet Security
Internet security refers to securing communication over the
Internet. It includes specific security protocols such as:

Internet Security Protocol (IPSec);

Secure Socket Layer (SSL).
3.1
Internet Security Protocol (IPSec)
It consists of a set of protocols designed by the Internet
Engineering Task Force (IETF). It provides security at network
level and helps to create authenticated and confidential
packets for the IP layer.
3.2
Secure Socket Layer (SSL)
It is a security protocol developed by Netscape
Communications Corporation. It provides security at transport
layer. It addresses the following security issues:

Privacy;

Integrity;

Authentication.
4
Threats
Internet security threats impact the network, data security and
other Internet connected systems. Cyber criminals have
evolved several techniques to threaten the privacy and
integrity of bank accounts, businesses and organisations.
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Following are some of the Internet security threats:

Mobile worms;

Malware;

PC and Mobile ransomware;

Large scale attacks like Stuxnet that attempt to destroy
infrastructure;

Hacking as a Service;

Spam;

Phishing.
5
Email Phishing
Email phishing is the activity of sending emails to a user
claiming to be a legitimate enterprise. Its main purpose is to
steal sensitive information such as usernames, passwords and
credit card details. Such emails contain links to websites that
are infected with malware and direct the user to enter details at
a fake website that looks and feels legitimate.
5.1
What a Phishing Email may contain?
Following are the symptoms of a phishing email:

Spelling and bad grammar — Most often such emails
contain grammatically incorrect text. Ignore such emails,
since it can be a spam;

Beware of links in email — Do not click on any links in
suspicious emails;

Threats — Such emails contain threat like “your account
will be closed if you did not respond to an email
message”;

Spoofing popular websites or companies — These
emails contain graphics that appear to be connected to a
legitimate website, but they actually are connected to
fake websites.
6
6.1
Data Encryption
Introduction
Encryption is a security method in which information is
encoded in such a way that only authorised users can read it.
It uses an encryption algorithm to generate cipher text that can
only be read if decrypted.
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Types of Encryption
There are two types of encryptions schemes as listed below:

Symmetric Key encryption;

Public Key encryption.
6.2.1
Symmetric Key Encryption
Symmetric key encryption algorithm uses same cryptographic
keys for both encryption and decryption of cipher text.
6.2.2
Public Key Encryption
Public key encryption algorithm uses pairs of keys, one of
which is a secret key and one of which is public. These two
keys are mathematically linked with each other.
6.3
Hashing
In terms of security, hashing is a technique used to encrypt
data and generate unpredictable hash values. It is the hash
function that generates the hash code, which helps to protect
the security of transmission from unauthorised users.
6.3.1
Hash Function Algorithms
Hashing algorithm provides a way to verify that the message
received is the same as the message sent. It can take a plain
text message as input and then computes a value based on
that message.
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Key Points:

The length of computed value is much shorter than the
original message;

It is possible that different plain text messages could
generate the same value.
Here we will discuss a sample hashing algorithm in which we
will multiply the number of a’s, e’s and h’s in the message and
will then add the number of o’s to this value.
For example, the message is “the combination to the safe is
two, seven, thirty-five”. The hash of this message, using our
simple hashing algorithm is as follows:
(2 x 6 x 3) + 4 = 40
The hash of this message is sent to John with cipher text. After
he decrypts the message, he computes its hash value using
the agreed upon hashing algorithm. If the hash value sent by
Bob does not match the hash value of decrypted message,
John will know that the message has been altered.
For example, John received a hash value of 17 and decrypted
a message Bob has sent as “You are being followed, use
backroads, hurry”.
He could conclude the message had been altered, this is
because the hash value of the message he received is:
(3 x 4 x 1) + 4 = 16
This is different from then value 17 that Bob sent.
7
7.1
Digital Signature
Digital Signature
Digital signatures allow us to verify the author, date and time of
signatures and authenticate the message contents. It also
includes authentication function for additional capabilities.
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A digital signature should not only be tied to the signing user,
but also to the message.
7.2
Applications
There are several reasons to implement digital signatures to
communications:

Authentication
Digital signatures help to authenticate the sources of
messages. For example, if a bank’s branch office sends
a message to central office, requesting for change in
balance of an account. If the central office could not
authenticate that message is sent from an authorised
source, acting upon such request could be a grave
mistake.

Integrity
Once the message is signed, any change in the
message would invalidate the signature.

Non-repudiation
By this property, any entity that has signed some
information cannot, at a later time, deny having signed it.
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Firewall Security
Firewall is a barrier between Local Area Network (LAN) and
the Internet. It allows keeping private resources confidential
and minimises the security risks. It controls network traffic in
both directions.
The following diagram depicts a sample firewall between LAN
and the Internet. The connection between the two is the point
of vulnerability. Both hardware and the software can be used
at this point to filter network traffic.
There are two types of Firewall systems: One works by using
filters at the network layer and the other works by using proxy
servers at the user, application or network layer.
Key Points

Firewall management must be addressed by both
system managers and the network managers;

The amount of filtering a firewall varies. For the same
firewall, the amount of filtering may be different in
different directions.
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Chapter 8: The Web and Web
Languages
1
What is WWW?
WWW stands for World Wide Web. A technical definition of the
World Wide Web is — all the resources and users on the
Internet that are using the Hypertext Transfer Protocol (HTTP).
A broader definition comes from the organisation that Web
inventor Tim Berners-Lee helped found, the World Wide Web
Consortium (W3C): The World Wide Web is the universe of
network-accessible information, an embodiment of human
knowledge.
In simple terms, The World Wide Web is a way of exchanging
information between computers on the Internet, tying them
together into a vast collection of interactive multimedia
resources.
2
What is HTTP?
HTTP stands for Hypertext Transfer Protocol. This is the
protocol being used to transfer hypertext documents that
makes the World Wide Web possible. A standard web
address, such as Yahoo.com, is called a URL and here the
prefix http indicates its protocol.
3
What is Website?
Currently you are on our website Tutorialspoint.com which is a
collection of various pages written in HTML mark-up language.
This is a location on the web where people can find tutorials on
the latest technologies. Similarly, there are millions of websites
available on the web. Each page available on the website is
called a web page and first page of any website is called home
page for that site.
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What is Web Server?
Every Website sits on a computer is known as a Web server.
This server is always connected to the Internet. Every Web
server that is connected to the Internet is given a unique
address made up of a series of four numbers between 0 and
256 separated by periods. For example: 68.178.157.132 or
68.122.35.127.
When you register a Web address, also known as a domain
name, such as tutorialspoint.com, you have to specify the IP
address of the Web server that will host the site.
We will see different type of Web servers in a separate
chapter.
5
What is W3C?
W3C stands for World Wide Web Consortium which is an
international consortium of companies involved with the
Internet and the web. The W3C was founded in 1994 by Tim
Berners-Lee, the original architect of the World Wide Web. The
organisation's purpose is to develop open standards so that
the web evolves in a single direction rather than being
splintered among competing factions. The W3C is the chief
standards body for HTTP and HTML.
6
Web — How it Works?
On the simplest level, the web physically consists of the
following components:

Your personal computer — This is the PC at which you
sit to see the web;

A Web browser — A software installed on your PC
which helps you to browse the Web;

An Internet connection — This is provided by an ISP
and connects you to the Internet to reach to any
website;

A Web server — This is the computer on which a
website is hosted;

Routers and Switches — They are the combination of
software and hardware that take your request and pass
it to the appropriate Web server.
The web is known as a client-server system. Your computer is
the client and the remote computers that store electronic files
are the servers.
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How the Web Works
When you enter something like Google.com the request goes
to one of many special computers on the Internet known as
Domain Name Servers (DNS). All these requests are routed
through various routers and switches. The domain name
servers keep tables of machine names and their IP addresses,
so that when you type in Google.com it gets translated into a
number, which identifies the computers that serve the Google
website to you.
When you want to view any page on the web, you must initiate
the activity by requesting a page using your browser. The
browser asks a domain name server to translate the domain
name you requested into an IP address. The browser then
sends a request to that server for the page you want, using a
standard called Hypertext Transfer Protocol or HTTP.
The server should constantly be connected to the Internet,
ready to serve pages to visitors. When it receives a request, it
looks for the requested document and returns it to the web
browser. When a request is made, the server usually logs the
client's IP address, the document requested and the date and
time it was requested. This information varies server to server.
An average web page actually requires the web browser to
request more than one file from the web server and not just the
HTML/ XHTML page, but also any images, style sheets and
other resources used in the web page. Each of these files,
including the main page, needs a URL to identify each item.
Then each item is sent by the web server to the web browser
and web browser collects all this information and displays them
in the form of web page.
6.2
In Short
We have seen how a web client/ server interaction happens.
We can summarise these steps as follows:

A user enters a URL into a browser (for example,
Google.com. This request is passed to a domain name
server;

The domain name server returns an IP address for the
server that hosts the website (for example:
68.178.157.132);

The browser requests the page from the web server
using the IP address specified by the domain name
server;
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
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The web server returns the page to the IP address
specified by the browser requesting the page. The page
may also contain links to other files on the same server,
such as images, which the browser will also request;
The browser collects all the information and displays to
your computer in the form of web page.
Web — Browser Types
Web browsers are software installed on your PC. To access
the web, you need a web browser, such as Netscape
Navigator, Microsoft Internet Explorer or Mozilla Firefox.
Currently you must be using any sort of web browser while you
are navigating through our site tutorialspoint.com. On the web,
when you navigate through pages of information, this is
commonly known as web browsing or web surfing.
There are four leading web browsers — Explorer, Firefox,
Netscape and Safari, but there are many others browsers
available. You might be interested in knowing Complete
Browser Statistics. Now we will see these browsers in bit more
detail.
While developing a site, we should try to make it compatible to
as many browsers as possible. Especially sites should be
compatible to major browsers like Explorer, Firefox, Chrome,
Netscape, Opera and Safari.
7.1
Internet Explorer®
Internet Explorer (IE) is a product from software giant
Microsoft. This is the most commonly used browser in the
universe. This was introduced in 1995 along with the Windows
95 launch and it has passed Netscape popularity in 1998.
7.2
Google Chrome®
This web browser is developed by Google and its beta version
was first released on September 2, 2008 for Microsoft
Windows. Today, Chrome is known to be one of the most
popular web browsers with its global share of more than 50%.
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Mozilla Firefox
Firefox is a new browser derived from Mozilla. It was released
in 2004 and has grown to be the second most popular browser
on the Internet.
7.4
Safari®
Safari is a web browser developed by Apple Inc. and included
in Mac OS X. It was first released as a public beta in January
2003. Safari has very good support for latest technologies like
XHTML, CSS2, etc.
7.5
Opera®
Opera is smaller and faster than most other browsers, yet it is
full-featured. Fast, user-friendly, with keyboard interface,
multiple windows, zoom functions and more. Java and nonJava-enabled versions are available. This web browser is ideal
for newcomers to the Internet, school children, the
handicapped and as a front-end for CD-ROM and kiosks.
7.6
Konqueror®
Konqueror is an open-source web browser with HTML 4.01
compliance, supporting Java applets, JavaScript, CSS1,
CSS2.1, as well as Netscape plugins. This works as a file
manager as well as it supports basic file management on local
UNIX filesystems, from simple cut/ copy and paste operations
to advanced remote and local network file browsing.
7.7
Lynx®
Lynx is a fully-featured World Wide Web browser for users on
Unix, VMS and other platforms running cursor-addressable,
character-cell terminals or emulators.
8
Web — Server Types
Every website sits on a computer known as a web server. This
server is always connected to the Internet. Every web server
that is connected to the Internet is given a unique address
made up of a series of four numbers between 0 and 255
separated by periods. For example: 68.178.157.132 or
68.122.35.127.
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When you register a web address, also known as a domain
name, such as tutorialspoint.com, you have to specify the IP
address of the web server that will host the site. You can load
up with Dedicated Servers that can support your web-based
operations.
There are four leading web servers — Apache®, IIS®,
lighttpd®, and Jagsaw®. Now we will see these servers in
more detail.
Apart from these web servers, there are other web servers
available in the market, but they are very expensive. Major
ones are Netscape's iPlanet, Bea's Web Logic and IBM's
WebSphere.
8.1
Apache HTTP Server®
This is the most popular web server in the world developed by
the Apache Software Foundation. Apache web server is an
open-source software and can be installed on almost all
operating systems including Linux, Unix, Windows, FreeBSD,
Mac OS X and more. About 60% of the web server machines
run the Apache Web Server.
8.2
Internet Information Services®
The Internet Information Server (IIS) is a high performance
web server from Microsoft. This web server runs on Windows
platforms. IIS comes bundled with Windows NT/2000 and
2003. because IIS is tightly integrated with the operating
system so it is relatively easy to administer it.
8.3
lighttpd®
The lighttpd, pronounced ‘lighty’ is also a free web server that
is distributed with the FreeBSD operating system. This opensource web server is fast, secure and consumes much less
CPU power. Lighttpd can also run on Windows, Mac OS X,
Linux and Solaris operating systems.
8.4
Sun Java System Web Server
This web server from Sun Microsystems is suited for medium
and large websites. Though the server is free, it is not open
source. It however, runs on Windows, Linux and Unix
platforms.
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The Sun Java System web server supports various languages,
scripts and technologies required for Web 2.0 such as JSP,
Java Servlets, PHP, Perl, Python, Ruby on Rails, ASP and
Coldfusion, etc.
8.5 Jigsaw® Server
Jigsaw (W3C's Server) comes from the World Wide Web
Consortium. It is open source, free and can run on various
platforms like Linux, Unix, Windows, Mac OS X and FreeBSD,
etc. Jigsaw has been written in Java and can run CGI scripts
and PHP programs.
9
Introduction to Web Languages
9.1
Hyper Text Mark-up Language
9.1.1
What is HTML?
HTML stands for Hyper Text Mark-up Language. This is the
language in which we write web pages for any website. This is
a subset of Standard Generalized Mark-Up Language (SGML)
for electronic publishing, the specific standard used for the
World Wide Web. It is a formatting language used to define the
appearance and contents of a web page. It allows us to
organise text, graphics, audio and video on a web page.
Key Points:

The word Hypertext refers to the text which acts as a
link;

The word mark-up refers to the symbols that are used to
define structure of the text. The mark-up symbols tell the
browser how to display the text and are often called
tags;

The word Language refers to the syntax that is similar to
any other language.
HTML was created by Tim Berners-Lee at CERN.
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HTML Versions
The following table shows the various versions of HTML:
Version
Year
HTML 1.0
1991
HTML 2.0
1995
HTML 3.2
1997
HTML 4.0
1999
XHTML
2000
HTML5
2012
9.3
HTML Tags
Tag is a command that tells the web browser how to display
the text, audio, graphics or video on a web page.
Key Points:

Tags are indicated with pair of angle brackets;

They start with a less than (<) character and end with a
greater than (>) character;

The tag name is specified between the angle brackets;

Most of the tags usually occur in pairs: the start tag and
the closing tag;

The start tag is simply the tag name is enclosed in angle
bracket whereas the closing tag is specified including a
forward slash (/);

Some tags are the empty, i.e. they do not have the
closing tag;

Tags are not case sensitive;

The starting and closing tag name must be the same.
For example <b> hello </i> is invalid as both are
different;

If you do not specify the angle brackets (< >) for a tag,
the browser will treat the tag name as a simple text;

The tag can also have attributes to provide additional
information about the tag to the browser.
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Basic tags
The following table shows the Basic HTML tags that define the
basic web page:
Tag
Description
<html> </html>
Specifies the document as a web page.
<head> </head>
Specifies the descriptive
about the web documents.
<title> </title>
Specifies the title of the web page.
<body> </body>
Specifies the body of a web document.
information
The following code shows how to use basic tags.
<html>
<head> Heading goes here…</head>
<title> Title goes here…</title>
<body> Body goes here…</body>
</html>
9.5
Formatting Tags
The following table shows the HTML tags used for formatting
the text:
Tag
Description
<b> </b>
Specifies the text as bold. E.g. this is
bold text.
<em> </em>
It is a phrase text. It specifies the
emphasised text. E.g. Emphasized text.
<strong> </strong>
It is a phrase tag. It specifies an important
text. E.g. this is strong text.
<i> </i>
The content of italic tag is displayed in
italic. E.g. Italic text.
<sub> </sub>
Specifies the subscripted text. E.g. X1
<sup> </sup>
Defines the superscripted text. E.g. X2
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Tag
Description
<ins> </ins>
Specifies the inserted text. E.g. The price
of pen is now 15.
<del> </del>
Specifies the deleted text. E.g. The price
of pen is now 15.
<mark> </mark>
Specifies the marked text. E.g. It is
raining.
9.6
Table Tags
Following table describe the commonly used table tags:
Tag
Description
<table> </table>
Specifies a table.
<tr> </tr>
Specifies a row in the table.
<th> </th>
Specifies header cell in the table.
<td> </td>
Specifies the data in a cell of the
table.
<caption> </caption>
Specifies the table caption.
<colgroup> </colgroup>
Specifies a group of columns in a
table for formatting.
9.7
List tags
Following table describe the commonly used list tags:
Tag
Description
<ul> </ul>
Specifies an unordered list.
<ol> </ol>
Specifies an ordered list.
<li> </li>
Specifies a list item.
<dl> </dl>
Specifies a description list.
<dt> </dt>
Specifies the term in a description list.
<dd> </dd>
Specifies description of term in a
description list.
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Frames
Frames help us to divide the browser’s window into multiple
rectangular regions. Each region contains separate HTML web
page and each of them work independently. A set of frames in
the entire browser is known as frameset. It tells the browser
how to divide the browser window into frames and the web
pages that each has to load.
The following table describes the various tags used for
creating frames:
Tag
Description
<frameset> </frameset>
It is replacement of the <body> tag.
It does not contain the tags that are
normally used in <body> element;
instead it contains the <frame>
element used to add each frame.
<frame> </frame>
Specifies the content of different
frames in a web page.
<base> </base>
It is used to set the default target
frame in any page that contains
links whose contents are displayed
in another frame.
9.9
Forms
Forms are used to input the values. These values are sent to
the server for processing. Forms use input elements such as
text fields, check boxes, radio buttons, lists and submit
buttons, etc. to enter the data into it.
The following table describes the commonly used tags while
creating a form:
Tag
Description
<form> </form>
It is used to create HTML form.
<input> </input>
Specifies the input field.
<textarea> </textarea>
Specifies a text area control that
allows to enter multi-line text.
<label> </label>
Specifies the label for an input
element.
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10 Cascading Style Sheet
10.1 Introduction
CSS is acronym of Cascading Style Sheets. It helps to define
the presentation of HTML elements as a separate file known
as CSS file having .css extension. CSS helps to change
formatting of any HTML element by just making changes at
one place. All changes made would be reflected automatically
to all of the web pages of the website in which that element
appeared.
10.2 CSS Rules
CSS Rules are the styles that we have to create in order to
create style sheets. These rules define appearance of
associated HTML element. The general form of CSS syntax is
as follows:
Selector {property: value;}
Key Points:

Selector is HTML element to which CSS rule is applied;

Property specifies the attribute that you want to change
corresponding to the selector;

Property can take specified value;

Property and Value are separated by a colon (:)’

Each declaration is separated by semi colon (;).
Following are examples of CSS rules:
P { color : red;}
h1 (color : green; font-style : italic }
body { color : cyan; font-family : Arial; font- style : 16pt}
10.3 Embedding CSS into HTML
Following are the four methods to add CSS to HTML
documents.
1.
Inline Style Sheets;
2.
Embedded Style Sheets;
3.
External Style Sheets;
4.
Imported Style Sheets.
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10.3.1 Inline Style Sheets
Inline Style Sheets are included with HTML element, i.e. they
are placed in line with the element. To add inline CSS, we
have to declare the style attribute which can contain any CSS
property.
Syntax:
<Tagname STYLE = “ Declaration1 ; Declaration2 “> ….
</Tagname>
Let us consider the following example using Inline Style
Sheets:
<p style="color: blue; text-align: left; font-size: 15pt">
Inline Style Sheets are included with HTML element i.e. they
are placed inline with the element.
To add inline CSS, we have to declare style attribute which
can contain any CSS property.
</p>
Output:
10.3.2 Embedded Style Sheets
Embedded Style Sheets are used to apply same appearance
to all occurrence of a specific element. These are defined in
<head> element by using the <style> element.
The <style> element must include type attribute. The value of
the type attribute specifies what type of syntax it includes when
rendered by the browser.
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Syntax:
<head> <title> …. </title>
<style type =”text/css”>
…….CSS Rules/Styles….
</head>
Let us consider the following example using Embedded Style
Sheets:
<style type="text/css">
p {color:green; text-align: left; font-size: 10pt}
h1 { color: red; font-weight: bold}
</style>
10.3.3 External Style Sheets
External Style Sheets are the separate .css files that contain
the CSS rules. These files can be linked to any HTML
documents using <link> tag with a rel attribute.
Syntax:
<head> <link rel= “stylesheet” type=”text/css” href= “url of css
file”>
</head>
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In order to create external CSS and link it to HTML document,
follow the following steps:

First of all create a CSS file and define all CSS rules for
several HTML elements. Let us name this file as
external.css:
p
{
Color: orange;
}
h1
{
Color: orange;
}

text-align: left;
font-size: 10pt;
font-weight: bold;
Now create HTML
as externaldemo.html:
document
and
name
it
<html>
<head>
<title> External Style Sheets Demo </title>
<link rel="stylesheet" type="text/css"
href="external.css">
</head>
<body>
<h1> External Style Sheets</h1>
<p>External Style Sheets are the separate .css files that
contain the CSS rules.</p>
</body>
</html>
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10.3.4 Imported Style Sheets
Imported Style Sheets allow us to import style rules from other
style sheets. To import CSS rules we have to use @import
before all the rules in a style sheet.
Syntax:
<head><title> Title Information </title>
<style type=”text/css”>
@import URL (cssfilepath)
… CSS rules…
</style>
</head>
</style>
Let us consider the following example using Inline Style
Sheets:
<html>
<head>
<title> External Style Sheets Demo </title>
<style>
@import url(external.css);
</style>
</head>
<body>
<h1> External Style Sheets</h1>
<p>External Style Sheets are the separate .css files that
contain the CSS rules.</p>
</body>
</html>
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11 JavaScript
11.1 Introduction
JavaScript is a lightweight, interpreted programming language
with object-oriented capabilities that allows you to build
interactivity into otherwise static HTML pages. JavaScript code
is not compiled, but translated by the translator. This translator
is embedded into the browser and is responsible for translating
JavaScript code.
Key Points:

It is a lightweight, interpreted programming language;

It is designed for creating network-centric applications;

It is complementary to and integrated with Java;

It is complementary to and integrated with HTML;

It is an open and cross-platform.
11.2 JavaScript Statements
JavaScript statements are the commands to tell the browser
what action to perform. Statements are separated by
semicolon (;). JavaScript statements constitute the JavaScript
code which is translated by the browser line by line.
Example of JavaScript statement:
document.getElementById("demo").innerHTML = "Welcome";
Following table shows the various JavaScript Statements:
Statement
Description
1.
switch
case
A block of statements in which execution of
code depends upon different cases. The
interpreter checks each case against the
value of the expression until a match is found.
If nothing matches, a default condition will be
used.
2.
If else
The if statement is the fundamental control
statement that allows JavaScript to make
decisions
and
execute
statements
conditionally.
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Statement
Description
3.
While
The purpose of a while loop is to execute a
statement or code block repeatedly as long as
expression is true. Once expression becomes
false, the loop will be exited.
4.
do while
Block of statements that are executed at least
once and continues to be executed while
conditions are true.
5.
for
Same as while, but initialisation, condition and
increment/ decrement are done in the same
line.
6.
for in
This loop is used to loop through an object's
properties.
7.
continue
The continue statement tells the interpreter to
immediately start the next iteration of the loop
and skip remaining code block.
8.
break
The break statement is used to exit a loop
early, breaking out of the enclosing curly
braces.
9.
function
A function is a group of reusable code which
can be called anywhere in your programme.
The keyword function is used to declare a
function.
10.
return
Return statement is used to return a value
from a function.
11.
var
Used to declare a variable.
12.
try
A block of statements on which error handling
is implemented.
13.
catch
A block of statements that are executed when
an error occurs.
14.
throw
Used to throw an error.
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11.3 JavaScript Comments
JavaScript supports both C-style and C++-style comments,
thus:

Any text between a // and the end of a line is treated as
a comment and is ignored by JavaScript;

Any text between the characters /* and */ is treated as a
comment. This may span multiple lines;

JavaScript also recognises the HTML comment opening
sequence <!--. JavaScript treats this as a single-line
comment, just as it does the // comment.-->;

The HTML comment closing sequence --> is not
recognised by JavaScript so it should be written as //-->.
Example:
<script language="javascript" type="text/javascript">
<!-// this is a comment. It is similar to comments in C++
/*
* This is a multiline comment in JavaScript
* It is very similar to comments in C Programming
*/
//-->
<script>
11.4 JavaScript Variable
Variables are referred to as named containers for storing
information. We can place data into these containers and then
refer to the data simply by naming the container.
11.4.1 Rules to Declare Variable in JavaScript
Here are the important rules that must be followed while
declaring a variable in JavaScript.

In JavaScript variable names are case sensitive, i.e. a is
different from A;

Variable name can only be started with a underscore
(_), a letter (from a to z or A to Z) or dollar ($) sign;

Numbers (0 to 9) can only be used after a letter;

No other special character is allowed in variable name.
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Before you use a variable in a JavaScript program, you must
declare it. Variables are declared with the var keyword as
follows:
<script type="text/javascript">
<!-var money;
var name, age;
//-->
</script>
Variables can be initialised at time of declaration or after
declaration as follows:
<script type="text/javascript">
<!-var name = "Ali";
var money;
money = 2000.50;
//-->
</script>
11.5 Javascript Data Type
There are two kinds of data types as mentioned below:

Primitive Data Type;

Non Primitive Data Type.
The following table describes Primitive Data Types available in
JavaScript:
Sr.No.
Datatype Description
1.
String
Can contain groups of characters as single value. It
is represented in double quotes. E.g. var x= “tutorial”.
2.
Numbers
Contains the numbers with or without decimal. E.g.
var x=44, y=44.56;
3.
Booleans
Contains only two values either true or false. E.g. var
x=true, y= false.
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Sr.No.
Datatype Description
4.
Undefined
Variable with no value is called Undefined. E.g. var x;
5.
Null
If we assign null to a variable, it becomes empty. E.g.
var x=null;
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The following table describes Non-Primitive Data Types in
JavaScript:
Sr.No.
Datatype Description
1.
Array
Can contain groups of values of same type. E.g. var
x={1,2,3,55};
2.
Objects
Objects are stored in property and value pair. E.g. var
rectangle = { length: 5, breadth: 3};
11.6 JavaScript Functions
Function is a group of reusable statements (Code) that can be
called anywhere in a program. In JavaScript function keywords
are used to declare or define a function.
Key Points:

To define a function use function keyword followed by
functionname, followed by parentheses ();

In parenthesis, we define parameters or attributes;

The group of reusable statements (code) is enclosed in
curly braces {}. This code is executed whenever function
is called.
Syntax:
function functionname (p1, p2) {
function coding…
}
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11.7 JavaScript Operators
Operators are used to perform operation on one, two or more
operands. An operator is represented by a symbol such as +,
=, *, %, etc. Following are the operators supported by
JavaScript:

Arithmetic Operators;

Comparison Operators;

Logical (or Relational) Operators;

Assignment Operators;

Conditional (or ternary) Operators;

Arithmetic Operators.
11.7.1 Arithmetic Operators
Following table shows all the arithmetic operators supported by
JavaScript:
Operator
Description
Example
+
Add two operands.
10 + 10 will give 20
-
Subtract second operand
from the first.
10 – 10 will give 0
*
Multiply two operands.
10 * 30 will give 300
/
Divide numerator by
denominator
10/10 will give 1
%
It is called modulus
operator and gives
remainder of the division.
10 % 10 will give 0
++
Increment operator,
increases integer value
by one
10 ++ will give 11
--
Decrement operator,
decreases integer value
by one
10 – will give 9
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11.7.2 Comparison Operators
Following table shows all the comparison operators supported
by JavaScript:
Operator
Description
Example
==
Checks if values of two operands
are equal or not. If yes then
condition becomes true.
10 == 10 will
give true
!=
Not Equal to operator
Checks if the value of two
operands is equal or not, if values
are not equal then condition
becomes true.
10 !=10 will
give false
>
Greater Than operator
Checks if the value of left operand
is greater than the value of right
operand, if yes then condition
becomes true.
20 > 10 will
give true
<
Less than operator
Checks if the value of left operand
is less than the value of right
operand, if yes then condition
becomes true.
10 < 20 will
give true
>=
Greater than or equal to
operator
Checks if the value of left operand
is greater than or equal to the
value of right operand, if yes then
condition becomes true.
10 >=20 will
give false
<=
Less than or equal to operator
Checks if the value of left operand
is less than or equal to the value
of right operand, if yes then
condition becomes true.
10 <=20 will
give true.
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11.7.3 Logical Operators
Following table shows all the logical operators supported by
JavaScript:
Operator
Description
Example
&&
Logical and operator returns
true if both operands are nonzero.
10 && 10 will give
true.
||
Logical or operator returns
true if any of the operand is
non-zero
10 || 0 will give
true.
!
Logical
not
operator
complements the logical state
of its operand.
! (10 && 10) will
give false.
11.7.4 Assignment Operators
Following table shows all the assignment operators supported
by JavaScript:
Operator
Description
Example
=
Simple Assignment
operator
Assigns values from right side
operands to left side operand.
C = A + B will
assign value of A
+ B into C
+=
Add and assignment
operator
It adds right operand to the
left operand and assigns the
result to left operand.
C += A is
equivalent to C =
C+A
-=
Subtract and assignment
operator
It subtracts right operand from
the left operand and assigns
the result to left operand.
C -= A is
equivalent to C =
C-A
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Operator
Description
Example
*=
Multiply and assignment
operator
It multiplies right operand with
the left operand and assigns
the result to left operand.
C *= A is
equivalent to C =
C*A
/=
Divide and assignment
operator
It divides left operand with the
right operand and assigns the
result to left operand.
C /= A is
equivalent to C =
C/A
%=
Modulus and assignment
operator
It takes modulus using two
operands and assigns the
result to left operand.
C %= A is
equivalent to C =
C%A
11.7.5 Conditional Operator
It is also called Ternary Operator, since it has three operands.
Operator
Description
Example
?:
Conditional
Expression
If Condition is true? Then value X :
Otherwise value Y
11.7.6 Control Structure
Control structure actually controls the flow of execution of a
program. The following are the several control structure
supported by JavaScript.

If … else;

Switch case;

Do while loop;

While loop;

For loop.
11.7.7 If … else
The ‘if’ statement is the fundamental control statement that
allows JavaScript to make decisions and execute statements
conditionally.
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Syntax:
if (expression){
Statement(s) to be executed if expression is true
}
Example:
<script type="text/javascript">
<!-var age = 20;
if( age > 18 ){
document.write("<b>Qualifies for driving</b>");
}
//-->
</script>
11.7.8 Switch Case
The basic syntax of the switch statement is to give an
expression to evaluate several different statements to execute
based on the value of the expression. The interpreter checks
each case against the value of the expression until a match is
found. If nothing matches, a default condition will be used.
Syntax:
switch (expression)
{
case condition 1: statement(s)
break;
case condition 2: statement(s)
break;
...
case condition n: statement(s)
break;
default: statement(s)
}
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Example:
<script type="text/javascript">
<!-var grade='A';
document.write("Entering switch block<br/>");
switch (grade)
{
case 'A': document.write("Good job<br/>");
break;
case 'B': document.write("Pretty good<br/>");
break;
case 'C': document.write("Passed<br/>");
break;
case 'D': document.write("Not so good<br/>");
break;
case 'F': document.write("Failed<br/>");
break;
default: document.write("Unknown grade<br/>")
}
document.write("Exiting switch block");
//-->
</script>
11.7.9 Do while Loop
The do...while loop is similar to the while loop except that the
condition check happens at the end of the loop. This means
that the loop will always be executed at least once, even if the
condition is false.
Syntax:
do{
Statement(s) to be executed;
} while (expression);
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Example:
<script type="text/javascript">
<!-var count = 0;
document.write("Starting Loop" + "<br/>");
do{
document.write("Current Count : " + count + "<br/>");
count++;
}while (count < 0);
document.write("Loop stopped!");
//-->
</script>
This will produce following result:
Starting Loop
Current Count : 0
Loop stopped!
11.7.10
While Loop
The purpose of a while loop is to execute a statement or code
block repeatedly as long as expression is true. Once
expression becomes false, the loop will be exited.
Syntax:
while (expression){
Statement(s) to be executed if expression is true
}
Example:
<script type="text/javascript">
<!-var count = 0;
document.write("Starting Loop" + "<br/>");
while (count < 10){
document.write("Current Count : " + count + "<br/>");
count++;
}
document.write("Loop stopped!");
//-->
</script>
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This will produce following result:
Starting Loop
Current Count : 0
Current Count : 1
Current Count : 2
Current Count : 3
Current Count : 4
Current Count : 5
Current Count : 6
Current Count : 7
Current Count : 8
Current Count : 9
Loop stopped!
11.7.11
For Loop
The For Loop is the most compact form of looping and
includes the following three important parts:

The loop initialisation where we initialise our counter to a
starting value. The initialisation statement is executed
before the loop begins;

The test statement which will test if the given condition is
true or not. If condition is true then code given inside the
loop will be executed otherwise loop will come out;

The iteration statement where you can increase or
decrease your counter.
Syntax:
for (initialization; test condition; iteration statement){
Statement(s) to be executed if test condition is true
}
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Example:
<script type="text/javascript">
<!-var count;
document.write("Starting Loop" + "<br/>");
for(count = 0; count < 10; count++){
document.write("Current Count : " + count );
document.write("<br/>");
}
document.write("Loop stopped!");
//-->
</script>
This will produce following result which is similar to while loop:
Starting Loop
Current Count : 0
Current Count : 1
Current Count : 2
Current Count : 3
Current Count : 4
Current Count : 5
Current Count : 6
Current Count : 7
Current Count : 8
Current Count : 9
Loop stopped!
11.8 Creating Sample Program
The following is the sample program that shows time, when we
click in button:
<html>
<body>
<button onclick="this.innerHTML=Date()">The time
is?</button>
<p>Click to display the date.</p>
<button onclick="displayDate()">The time is?</button>
<script>
function displayDate() {
document.getElementById("demo").innerHTML = Date();
}</script>
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<p id="demo"></p>
</body>
</html>
12 Hypertext Pre-processor (PHP)
12.1 Introduction
PHP is acronym of Hypertext Pre-processor (PHP) and is a
programming language that allows web developers to create
dynamic content that interacts with databases. PHP is
basically used for developing web-based software applications.
PHP started out as a small open source project that evolved as
more and more people found out how useful it was. Rasmus
Lerdorf unleashed the first version of PHP way back in 1994.
Key Points:

PHP is a recursive acronym for "PHP: Hypertext Preprocessor";

PHP is a server-side scripting language that is
embedded in HTML. It is used to manage dynamic
content, databases, session tracking and even build
entire e-commerce sites;

It is integrated with a number of popular databases,
including MySQL, PostgreSQL, Oracle, Sybase, Informix
and Microsoft SQL Server;

PHP is pleasingly zippy in its execution, especially when
compiled as an Apache module on the Unix side. The
MySQL server, once started, executes even very
complex queries with huge result sets in record-setting
time;

PHP supports a large number of major protocols such
as POP3, IMAP and LDAP. PHP4 added support for
Java and distributed object architectures (COM and
CORBA), making n-tier development a possibility for the
first time.
12.2 Uses of PHP
PHP has now become a popular scripting language among
web developers due to the following reasons:

PHP performs system functions, i.e. from files on a
system it can create, open, read, write and close them;
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




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PHP can handle forms, i.e. gather data from files, save
data to a file, through email you can send data and
return data to the user;
You add, delete and modify elements within your
database through PHP;
Access cookies variables and set cookies;
Using PHP, you can restrict users to access some
pages of your website;
It can encrypt data.
12.3 Characteristics
Five important characteristics make PHP's practical nature
possible:

Simplicity;

Efficiency;

Security;

Flexibility;

Familiarity.
12.4 "Hello World" Script in PHP
To get a feel for PHP, first start with simple PHP scripts. Since
"Hello, World!" is an essential example, first we will create a
friendly little "Hello, World!" script.
As mentioned earlier, PHP is embedded in HTML. That means
that in amongst your normal HTML (or XHTML if you are
cutting-edge) you will have PHP statements like this:
<html>
<head>
<title>Hello World</title>
</head>
<body>
<?php echo "Hello, World!";?>
</body>
</html>
It will produce following result:
Hello, World!
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If you examine the HTML output of the above example, you will
notice that the PHP code is not present in the file sent from the
server to your web browser. All of the PHP present in the web
page is processed and stripped from the page; the only thing
returned to the client from the web server is pure HTML output.
All PHP code must be included inside one of the three special
mark-up tags ate are recognised by the PHP Parser.
<?php PHP code goes here ?>
<? PHP code goes here ?>
<script language="php"> PHP code goes here </script>
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Bibliography
An Internet of Things: Examples. Available at: http://www.postscapes.com/Internetof-things-examples/[Date Accessed: 16 January 2017]
A Simple Tutorial – Manual. Available at: http://php.net/manual/en/tutorial.php [Date
Accessed: 16 January 2017]
Computer Security Threats. Available at:
https://www.webroot.com/za/en/home/resources/articles/pc-security/computersecurity-threats [Date Accessed: 16 January 2017]
Common Threats to be Aware of. Available at:
https://www.getcybersafe.gc.ca/cnt/rsks/cmmn-thrts-en.aspx [Date Accessed: 16
January 2017]
Firewall Security. Available at:
http://www.cisco.com/c/en/us/products/security/firewalls/what-is-a-firewall.html [Date
Accessed: 16 January 2017]
IoT Council. 2016. Internet of Things. Available at http://www.theInternetofthings.eu/
[Date Accessed: 16 January 2017]
JavaScript for the Total Non-Programmer. Available at:
http://www.webteacher.com/javascript/ [Date Accessed: 16 January 2017]
Internet Society. 2017. History of the Internet. Available at:
https://www.Internetsociety.org/Internet/what-Internet/historyInternet?gclid=Cj0KEQiAuJXFBRDirIGnpZLE-N4BEiQAqV0KGtXcW-ult0g8axWrFcPEgUxrOUOYNjn94ez76aynWsaAhII8P8HAQ [Date Accessed: 16 January
2017]
NetworkWorld. 2009. The evolution of the Internet. Available at:
http://www.networkworld.com/article/2870267/lan-wan/the-evolution-of-theInternet.html [Date Accessed: 16 January 2017]
Web Services Explained. Available at: http://www.servicearchitecture.com/articles/web-services/web_services_explained.html [Date
Accessed: 16 January 2017]
The search Engine List. Available at: http://www.thesearchenginelist.com/ [Date
Accessed: 16 January 2017]
Reference Models in Communication Networks. Available at:
http://www.studytonight.com/computer-networks/reference-models [Date Accessed:
16 January 2017]
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OSI Seven Layers Model Explained with Examples. Available at:
http://www.studytonight.com/computer-networks/reference-models [Date Accessed:
16 January 2017]
Networking tutorials for Beginners: Get Your Basics Right. Available at:
https://blog.udemy.com/networking-tutorials-for-beginners/ [Date Accessed: 16
January 2017]
How
TCP/IP
Works.
Available
ate:
https://technet.microsoft.com/enus/library/cc786128(v=ws.10).aspx [Date Accessed: 16 January 2017]
HTML Basics, Available at:
http://www.htmlgoodies.com/primers/html/article.php/3478131 [Date Accessed: 16
January 2017]
How Encryption Work. Available at:
http://computer.howstuffworks.com/encryption.htm [Date Accessed: 16 January
2017]
Internet Collaboration. Available at: http://www.Internetcollaboration.org/ [Date
Accessed: 16 January 2017]
Internet is All about Collaboration. Available at:
https://www.Internetsociety.org/blog/tech-matters/2015/04/Internet-all-aboutcollaboration [Date Accessed: 16 January 2017]
Internet of Things. Available at: http://www.cisco.com/c/en/us/solutions/Internet-ofthings/overview.html [Date Accessed: 16 January 2017]
Subnetting. Available at: https://technet.microsoft.com/en-us/library/cc958834.aspx
[Date Accessed: 16 January 2017]
Starting with HTML + CSS. Available at:
https://www.w3.org/Style/Examples/011/firstcss.en.html [Date Accessed: 16 January
2017]
SANS. 2017. Network Security. Available at: https://www.sans.org/networksecurity/#free [Date Accessed: 16 January 2017]
TCP/IP Tools and Settings:
https://technet.microsoft.com/en-us/library/cc786724(v=ws.10).aspx [Date Accessed:
16 January 2017]
TCP/IP Protocol Architecture. Available at: https://technet.microsoft.com/enus/library/cc958821.aspx [Date Accessed: 16 January 2017]
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The Internet of Things is Far Bigger than Anyone Realised. Available at:
https://www.wired.com/insights/2014/11/the-Internet-of-things-bigger/ [Date
Accessed: 16 January 2017]
The 10 Most Common Security Threats Explained. Available at:
http://blogs.cisco.com/smallbusiness/the-10-most-common-security-threats-explained
[Date Accessed: 16 January 2017]
The Beginner’s Guide to Encryption. Available at: http://lifehacker.com/a-beginnersguide-to-encryption-what-it-is-and-how-to-1508196946[Date Accessed: 16 January
2017]
TutorialsPoint. Available at: http://www.tutorialspoint.com [Date Accessed: 01
November 2016]
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Intellectual Property
Plagiarism occurs in a variety of forms. Ultimately though, it refers to the use of the
words, ideas or images of another person without acknowledging the source using
the required conventions. The IIE publishes a Quick Reference Guide that provides
more detailed guidance, but a brief description of plagiarism and referencing is
included below for your reference. It is vital that you are familiar with this information
and the Intellectual Integrity Policy before attempting any assignments.
Introduction to Referencing and Plagiarism
What is ‘Plagiarism’?
‘Plagiarism’ is the act of taking someone’s words or ideas and presenting them as
your own.
What is ‘Referencing’?
‘Referencing’ is the act of citing or giving credit to the authors of any work that you
have referred to or consulted. A ‘reference’ then refers to a citation (a credit) or the
actual information from a publication that is referred to.
Referencing is the acknowledgment of any work that is not your own, but is used by
you in an academic document. It is simply a way of giving credit to and
acknowledging the ideas and words of others.
When writing assignments, students are required to acknowledge the work, words or
ideas of others through the technique of referencing. Referencing occurs in the text
at the place where the work of others is being cited, and at the end of the document,
in the bibliography.
The bibliography is a list of all the work (published and unpublished) that a writer has
read in the course of preparing a piece of writing. This includes items that are not
directly cited in the work.
A reference is required when you:

Quote directly: when you use the exact words as they appear in the source;

Copy directly: when you copy data, figures, tables, images, music, videos or
frameworks;

Summarise: when you write a short account of what is in the source;

Paraphrase: when you state the work, words and ideas of someone else in
your own words.
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It is standard practice in the academic world to recognise and respect the ownership
of ideas, known as intellectual property, through good referencing techniques.
However, there are other reasons why referencing is useful.
Good Reasons for Referencing
It is good academic practice to reference because:

It enhances the quality of your writing;

It demonstrates the scope, depth and breadth of your research;

It gives structure and strength to the aims of your article or paper;

It endorses your arguments;

It allows readers to access source documents relating to your work, quickly and
easily.
Sources
The following would count as ‘sources’:

Books,

Chapters from books,

Encyclopaedia,

Articles,

Journals,

Magazines,

Periodicals,

Newspaper articles,

Items from the Internet (images, videos, etc.),

Pictures,

Unpublished notes, articles, papers, books, manuscripts, dissertations, theses,
etc.,

Diagrams,

Videos,

Films,

Music,

Works of fiction (novels, short stories or poetry).
What You Need to Document from the Hard Copy Source You
are Using
(Not every detail will be applicable in every case. However, the following lists provide
a guide to what information is needed.)
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You need to acknowledge:

The words or work of the author(s),

The author(s)’s or editor(s)’s full names,

If your source is a group/ organisation/ body, you need all the details,

Name of the journal, periodical, magazine, book, etc.,

Edition,

Publisher’s name,

Place of publication (i.e. the city of publication),

Year of publication,

Volume number,

Issue number,

Page numbers.
What You Need to Document if you are Citing Electronic
Sources







Author(s)’s/ editor(s)’s name,
Title of the page,
Title of the site,
Copyright date, or the date that the page was last updated,
Full Internet address of page(s),
Date you accessed/ viewed the source,
Any other relevant information pertaining to the web page or website.
Referencing Systems
There are a number of referencing systems in use and each has its own consistent
rules. While these may differ from system-to-system, the referencing system followed
needs to be used consistently, throughout the text. Different referencing systems
cannot be mixed in the same piece of work!
A detailed guide to referencing, entitled Referencing and Plagiarism Guide is
available from your library. Please refer to it if you require further assistance.
When is Referencing Not Necessary?
This is a difficult question to answer – usually when something is ‘common
knowledge’. However, it is not always clear what ‘common knowledge’ is.
Examples of ‘common knowledge’ are:

Nelson Mandela was released from prison in 1990;

The world’s largest diamond was found in South Africa;

South Africa is divided into nine (9) provinces;

The lion is also known as ‘The King of the Jungle’.

𝐸 = 𝑚𝑐 2

The sky is blue.
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Usually, all of the above examples would not be referenced. The equation 𝐸 = 𝑚𝑐 2
is Einstein’s famous equation for calculations of total energy and has become so
familiar that it is not referenced to Einstein.
Sometimes what we think is ‘common knowledge’, is not. For example, the above
statement about the sky being blue is only partly true. The light from the sun looks
white, but it is actually made up of all the colours of the rainbow. Sunlight reaches the
Earth's atmosphere and is scattered in all directions by all the gases and particles in
the air. The smallest particles are by coincidence the same length as the wavelength
of blue light. Blue is scattered more than the other colours because it travels as
shorter, smaller waves. It is not entirely accurate then to claim that the sky is blue. It
is thus generally safer to always check your facts and try to find a reputable source
for your claim.
Important Plagiarism Reminders
The IIE respects the intellectual property of other people and requires its students to
be familiar with the necessary referencing conventions. Please ensure that you seek
assistance in this regard before submitting work if you are uncertain.
If you fail to acknowledge the work or ideas of others or do so inadequately this will
be handled in terms of the Intellectual Integrity Policy (available in the library) and/ or
the Student Code of Conduct – depending on whether or not plagiarism and/ or
cheating (passing off the work of other people as your own by copying the work of
other students or copying off the Internet or from another source) is suspected.
Your campus offers individual and group training on referencing conventions –
please speak to your librarian or ADC/ Campus Co-Navigator in this regard.
Reiteration of the Declaration you have signed:
1.
I have been informed about the seriousness of acts of plagiarism.
2.
I understand what plagiarism is.
3.
I am aware that The Independent Institute of Education (IIE) has a policy
regarding plagiarism and that it does not accept acts of plagiarism.
4.
I am aware that the Intellectual Integrity Policy and the Student Code of
Conduct prescribe the consequences of plagiarism.
5.
I am aware that referencing guides are available in my student handbook or
equivalent and in the library and that following them is a requirement for
successful completion of my programme.
6.
I am aware that should I require support or assistance in using referencing
guides to avoid plagiarism I may speak to the lecturers, the librarian or the
campus ADC/ Campus Co-Navigator.
7.
I am aware of the consequences of plagiarism.
Please ask for assistance prior to submitting work if you are at all unsure.
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