ARPANet was the first wide-area network created by the US Defense Department in 1969. It served as a testbed for new networking technologies and evolved into the modern Internet. The World Wide Web (WWW) is a system of interlinked hypertext documents accessed via the Internet using browsers. It allows users to view web pages that contain text, images, videos and other multimedia. Each web page is made up of HTML code and can contain links to other pages located on different servers around the world.

1. Sub topic : ARPANet and WWW
.
* 1

2. Recap
In the previous class, you have learnt about
• Definition of a bridge
• Importance of a bridge
• Types of bridges
• Functioning of a bridge
• Definition of a gateways
• Function of gateways
* 2

3. Objectives
On completion this topic, you would be able to know
about
• ARPA Net (Advanced Research Project Agency Net)
• WWW (World Wide Web)
* 3

4. ARPA Network
• Advanced Research Project Agency (ARPA) was established
in 1969
• ARPANET was a large wide – area network created by the
United States Defense Department
• ARPANET served as a test bed for new networking
technologies, linking many Universities and research centers
* 4

5. ARPA Network contd….
• The first two nodes that formed the ARPANET were
UCLA and the Standard Research Institute
• It has evolved into the Internet
• When the ARPANET migrated to the internet protocols in
1983, the major application protocols migrated along
with it
* 5

6. E-mail
• In 1971, Ray Tomlinson of BBN sent the first network
email
• By 1973, 75% of the ARPA net traffic was email
File Transfer
• By 1973, the File Transfer Protocol (FTP)
specification had been defined and implemented,
enabling file transfer over the ARPANET
* 6

7. Voice Traffic
• A Network Voice Protocol (NVP) specifications was
also defined (RFC 741) and then implemented
* 7

8. ARPA Network contd….
• Network that has worldwide broadcasting capability, a
mechanism for information dissemination, and a medium for
collaboration , interaction between individuals and their
computers regardless of their geographical location
• The internet is a packet switched global network system that
consists of millions of local area networks and computers
* 8

9. ARPA Network contd….
• In 1983, the U.S military portion of the ARPANET was
broken off as a separate network the MILNET
• Prior to this the ARPA consists of 113 nodes after that
the MILNET consists of 68nodes
* 9

10. World Wide Web (WWW)
• The WWW (world wide web) is a system of interlinked,
hypertext documents accessed via the internet
• With a web browser, a user views web pages that may
contain text, images video and other multimedia
• .WWW are commonly found at the beginning of web
addresses
* 10

11. World Wide Web (WWW) contd….
• The www today is a distributed client / server service , in
which client using a browser can access a service using
a server
• The service provided is distributed over many locations
called ‘sites’
• Each site holds one or more documents referred to as
web pages
* 11

12. World Wide Web (WWW) contd….
• A web page is made up of two parts. The head and the
body
• The head is the first part of a web page. The head contains
the title of the page and other parameters that the browser
will use
• The actual contents of a page are in the body, which
includes text and the tag
* 12

13. World Wide Web (WWW) contd….
• Each web page can contain a link to other pages
• The web pages are written in the HTML language i.e.
Hyper Text Mark up Language
• Web server is a program running on a server computer
* 13

14. World Wide Web (WWW) contd….
• The web server constantly waits for a request for a web
page from browser program which runs on the client
• HTTP i.e. Hyper Text Transfer Protocol is a protocol
used mainly to access data on the www, which governs
the dialog between the client and server
* 14

15. Architecture of www
Site A Site B
client
Request
Web page A
Request
Web page B Fig .1
* 15

16. Architecture of www contd….
• Each web page can contain a link to other pages. The
client needs to see some information that belongs to site A
• Site A sends a request through its browser, that is
designed to fetch web documents
• Along other information the request includes the address of
the site and the web page called URL
* 16

17. Architecture of www contd….
• The URL (Uniform Resource Locator) consists of for
example
http// www. yahoo. com / index
Protocol to be used
Domain name space Document / file name
* 17

18. Architecture of www contd….
• The server at site A finds the document and sends it to
the client
• When the user views the document, she finds some
references to other documents, including a web page at
site B
* 18

19. Summary
In this class, you have learnt about
• ARPANET
• WWW and its Architecture
* 19

20. Quiz
1) URL stands for ____________________________
a) Uniform resource locator
b) Uniform register locator
c) Universal resource locator
20

21. Frequently Asked Questions
1. Explain briefly about www
2. Write short notes on ARPANET
21