The Internet
UNIT 1
THE INTERNET
Structure 1.0 1.1 1.2 1.3 1.4 1.5 1.6
Introduction Objectives Classification of Networks Networking Models What is Packet Switching? Accessing the Internet Internet Protocols 1.6.1 1.6.2
1.7
1.12 1.13 1.14
1.0
16 17 18 21
Domain Name System SMTP and Electronic Mail Http and World Wide Web Usenet and Newgroups FTP Telnet
Internet Tools 1.12.1 1.12.2
14
Structure of Internet Servers Address Address Space
How does the Internet Work? Intranet & Extranet Internet Infrastructure Protocols and Services on Internet 1.11.1 1.11.2 1.11.3 1.11.4 1.11.5 1.11.6
5 6 6 7 10 10 12
Internet Protocol (IP) Transmission Control Protocol (TCP)
Internet Address 1.7.1 1.7.2
1.8 1.9 1.10 1.11
Page No.
27
Search Engines Web Browser
Summary Solutions/ Answers
28 28
INTRODUCTION
The Internet is worldwide computer network that interconnects, million of computing devices throughout the world. Most of these devices are PC’s, and servers that store and transmit information such as web pages and e-mail messages. Internet is revolutionizing and enhancing the way we as humans communicate, both locally and around the globe. Everyone wants to be a part of it because the Internet literally puts a world of information and a potential worldwide audience at your fingertips. The Internet evolved from the ARPANET (Advanced Research Projects Agency) to which other networks were added to form an inter network. The present Internet is a collection of several hundred thousand of networks rather than a single network. From there evolved a high-speed backbone of Internet access for sharing these of networks. The end of the decade saw the emergence of the World Wide Web, which heralded a platform-independent means of communication enhanced with a pleasant and relatively easy-to-use graphical interface. World Wide Web is an example of an information protocol/service that can be used to send and receive information over the Internet. It supports: x x x
Multimedia Information (text, movies, pictures, sound, programs . . . ). HyperText Information (information that contains links to other information resources). Graphic User Interface (so users can point and click to request information instead of typing in text commands).
The World Wide Web model follows Cient/Server software design. A service that uses client/server design requires two pieces of software to work: Client Software, 5