Internet 197

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INTERNET -- A Curtain Raiser !

1.Introduction about Internet

2. Internet Trunking Diagram

3. Protocols

4.Accessing and Accounting5.Facilities offered by Internet

6.Terminologies

7.Search Engines

8. Connection requirements

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Internet

• is a network of networks

• is a packet switching network

• is cooperative interconnection of

dissimilar computing networks

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Genesis of Internet

ARPANET : Advanced Research Project

Administration

MILNET : Military Net

NSFNET : National Science Foundation

Network INTERNET: INTER connection of NET work

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Used for Commercial and business developments at

relatively low cost.

To get free informations on non profit organisations.

To get informations on Archives of free or sharewaresoftware.

Why Internet?

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♦ No one owns Internet

♦ Every person who makes a connection owns a

slice of Internet

♦ Ultimate authority “INTERNET society”♦ IAB - Internet Architecture Board for

technical management

Who owns Internet?

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♦ No one pays

♦ Instead every one pays for their part

∇ A college or corporation pays for theirconnection to some Regional network, which in

turn pays a National provider for its access.

Who pays?

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♦ INET - Do not use protocols of Internet

♦ Intranet - Network meant for within the

Organisation

What is not Internet?

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PC with

emulation

software IP Router

V S N L

I n

t e r n

e t

H o s

t

Internet Network

PSTN

Dial UP

Terminal Server

VSNL GIAS

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Protocol• The accepted modes of communication amongst

computers are known as communication protocol.

• Data to be transmitted is converted into small

packets.

• The software that makes internet functionefficiently is TCP/IP.

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Protocol:

• TCP/IP is made up of two

components.– TCP guarantees the integrity ofthe data

– IP ensures the routing of packetsto the desired destination

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Accessing Internet

Internet can be accessed through

•A dedicated connection or

•A dial-up connection

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Internet Accounts:

A dial up access can be of

two kinds:

• TCP/IP Accounts

•Graphics and Text

• Shell Accounts•Text only

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Addressing System:

The system of addressing in the internet is called IP

addressing system and comprises:

• Letter Addressing System(Domain addressing)

more...

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• Number Addressing System (IP addressing)

Doted Quad

Each number in the doted quad is called an Octet

202.150.52.39

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URL : Uniform Resource Locator

A Web Addressing Scheme that spells out theexact location of a net Resource.

°<protocol>://<host domain>/<directory>/<filename>

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URL : Uniform Resource Locator

A Web Addressing Scheme that spells outthe exact location of a net Resource.

°<protocol>://<host domain>/<directory>/<filename>Example:

°http://www.tamilnadu-telecom.com/profile

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An example of a letter address is:

The three letters ‘net’ provides the kind of

organisation. The last two letters ‘in’ denotes the countr code.

Gate

way

Ser ver

No.

Ser vice

provi

der

Typeof

Orgn.

Loca

tion

User

name

Country

[email protected]

I f ili i ff d b

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veronica

archie

wais

FTP

TELNET

WWW

Important facilities offered by

INTERNET

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Email

The most common of thecommunication methods used by peopleon the internet is the private letter,written by one individual to another

indvidual recipient or through anInternet email gateway to or from aservice which provides an Internetgateway.

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Gopher

•an internet based document retrieval system.

•the internet offers a fascinating world called theGOPHER SPACE.

•allows you to gather information from across theInternet that could be of text, images,sound and

services in the form of Telnet connections.•is menu driven and very simple to operate.

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NEWSGROUPA newsgroup is a place where you can postnotices, messages or questions for others tosee and reply to with a posting of theirown.

There are about 18,000 newsgroup inInternet hosted by a large network calledusenet.

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Veronica:

•Very Easy Rodent Oriented Netwide Index to ComputerArchives.

• It is an index of titles and Internet Gopher items,which is updated once in every fortnight andprovides keyword searches of those titles

•A veronica search typically searches the menus of

hundreds of Gopher servers.

• Once the file has been located, Veronica allows tobrowse through them.

• Veronica is also very easy to use as it is menu driven..

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ARCHIE:•is a program written to help us to find files and

the hosts upon which they are stored.

•the name Archie refers to both the clientprogramme running on many host computersand to the several Archie servers located ingeographically separated places around theworld.

•the server programmes contain directory of thenames of files available in directories.

•this directory is periodically updated.

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WAIS (Wide Area Information System)

•This helps us to locate text documents.The

search is based on the keyword provided.•keeps track of how many times the keyword is

found in documents.

•identifies documents after calculating whichdocument is most closely related to ourtopic. It finds exact matches.

•if we are searching for Ram, WAIS will ignoreRamakrishnan, Ramkumar and so on.

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FTP•an Internet tool that copies a file from an

Internet site to another.

•FTP stands for both file transfer protocoland file transfer programme., thespecific program one that implementsthe transfer.

• With the internet address or domain nameof a site, we can use FTP to connectto a specific location on the site andcopy a file containing information to

and from our computer for our ownuse.

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TELNET

*an internet tool that lets you travelfrom your own workstation out intothe cyberspace.

* We can communicate with a widevariety of remote systems with whomwe have an account.

* is widely used to access databasesand explore public access computersystems.

* is frequently used by libraries.

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World Wide Web

»Millions of webservers

located worldwide andconnected through TCP /IPand HTTP constitute the

World Wide Web.

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Web Server:

»Computers can communicate

through Telecom Networks.»A computer configured to deliver

and accept information by accepted

modes of communication between

computers --connected to a telecommunication

network --

ɖ is called a WEB SERVER.

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Website»A website is a virtual bookor a brochure of anorganisation or a company.

»It is a set of related

webpages, containinginformation about aparticular organisation or a

topic.

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Web page

»The information from a web server

is accessed in units of computer fileswhich can contain beside text,

graphic images, sound files and

videoclips organised to appear on a

computer monitor screen at aninstance constitute a WEBPAGE.

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Home Page

*First hypertextdocument

displayed when alink to web serveris established

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HTML

* Hyper Text MarkupLanguage.

* Encoding Scheme toformat web document.

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Hyper link

»A hyperlink is a section of the

text or an image (appearing ona web page), which has theaddress of another web pageembedded in it.

»Thus the web pages on theinternet are related to eachother through hyperlinks.

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BROWSER

»A client softwarethat allows to display

and interact withhypertext document.

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Web Browsers:

Web Browsers are tools that help the

user to

• View documents, graphic files

• Entertain by using multimedia

facilities (audio, video)

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Some of the Web Browsers are

#INTERNET EXPLORER

#NETSCAPE COMMUNICATOR

#MOSAIC

#OPERA

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Surfing the web is alsoknown as NAVIGATINGTHE WEB.

Navigation of web can be done by two ways:

• Common addressing scheme called URL

(uniform resource locator)

•Web search engines

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A SEARCH ENGINE is just a website designed toperform searches of the net.

Most search engines allow you to enter very specific, evencomplicated search queries.A single keyword - or a couple for a narrower search willusually do the job.

Some of the

search engines are:

YAHOO

LYCOS

KHOJ

ALTAVISTA

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Internet 197

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