The Internet



The Internet is a network of networks . It is a global collection of high-powered computers that are connected to each other with network cables, telephone lines, microwave dishes, satellites etc. Some computers (Servers) on the Internet store documents, sound files, video clips, program files, electronic shopping centers, animations , pictures, interactive contents and other information that can be stored and presented electronically. All these resources are available to all computers connected to the Internet.

A Network of Networks

The Internet mainly connects of computers . In a corporate wide network. Each department has a Local Network that allows sharing of files, databases, printers and other peripheral devices. Several departments working together interconnect their networks so that the information may be shared more easily among the departments. This type of arrangement called a regional network. These regional networks are interconnections based on geography or function. The regional networks are connected to the corporate network, this is also called a backbone. The gateways are the physical meeting points of backbones.

Gateway

A Gateway is a communication device or program that passes data between networks having similar functions but dissimilar implementations.

Connecting to the Internet

❖ An account with Internet Service Provider (ISP) is a must connect to the Internet. In India VSNL (Videsh Sanchar Nigam Ltd.) is one of the Internet Service Providers.

❖ Individual computers can establish the connection with ISP's servers. A username and a password restriction is used to connect to the main server. Direct cable connection and dial-up networking (Using telephone liens and modem) are the ways to connect your machine to ISP's servers.

❖ In case of dial-up networking, telephone lines and modems are used to connect the local ISP. In this kind of connection user, must dial the ISP's phone numbers to establish the connection. In copper wires( telephone lines) digital data can not travel. So digital data is converted into analog signals and transmitted . The speed of the connection is determined based on the status of the telephone system. If telephone system uses copper wires, the speed of the data flow cannot exceed 64 Kbps.

❖ Internet Browser brings the Internet to your system . Web browsers enable you to use most of the Internet features like sending and receiving mail, downloading files from the Internet, browsing documents on the Net and reading and posting in News Groups, Netscape Navigator and messages and Microsoft Internet Explorer are the two most popular Web browsers. These browsers can be used to watch videos on the Web, listen to music , read a book and even to shop.

Internet Service Providers

The cheapest way to surf the Internet is to get a connection from your local Internet Service provider (ISP). The ISP takes you to the Internet. ISP will charge you periodically for the Internet access. Your ISP may also charge you an initial setup fee. If you are accessing the Internet from within Windows, you will required SLIP (Serial line input protocol) or PPP (Point to Point Protocol) Connection. VSNL, MTNL and Satyma Online are the popular Internet service Providers in India. They have DNS servers in many cities throughout India. SLIP and PPP are two popular protocols that allow home computer users to connect their computers to the Internet as peer hosts. IN this mode of connection host computer will be able to browse the network individually without any interruption from the server. For TCP/IP connection Internet. Service Provider must have PPP and SLIP protocols.

DNS Servers

DNS server is a computer that translates the domain name of another computer into an IP (Internet Protocol) address, and vice versa on request. Every computer in the network has an IP address, which specifies its physical network connection. To locate the information in Internet two kind of addresses can be used. These are domain names and IP addresses. Domain names follow a format called Domain Name system.

Connection Types

❖ In a host /terminal connection or shell account , your computer acts as if it were a terminal directly connected to an internet to an internal host. Terminal emulation programs (Windows Terminal) can be used to make your computer act as a terminal. The terminal program signals the modem to dial and handles the transfer of characters from your computer to the host computer and back. This account does not permit the download of graphics, video or audio from web sites. IT is less expensive.

❖ TCP/IP link allows your computer to function an as internet host. These links are called either SLIP (Serial Line Internet Protocol) Or PPP ( Point to Point Protocol ) links. Using this account direct e-mail, some sort of news group access, FTP, Telnet and running browser software is possible . This account is more expensive and allows for graphics download.

A Note on Modems

A modem is required when connecting to Internet using telephone lines. IT is an essential link between the computer running internet browser and Dial-up service provider. The achieve this form of connection the data, which is stored on the computer in digital form, needs to be translated to an analog from to be computer in digital form, needs to be translated to an analog form to be transmitted over the telephone lines. A hardware device MODEM (Modulator-Demodulator) is employed to affect the conversion. The modem must be connected to computer and the telephone on both ends.

Modem speeds are measured in terms of BPS . Speeds available are 9600 BPS, 28800 BPS , 33600 BPS etc, Connecting speed is dependent on the telephone service called ISDN< which can allow a modem to connect at 128 KBPS. This service is provided by DOT and costs more than the regular analog connection. IT also requires additional hardware. However connecting ISDN connection provide fastest access and highest quality connection, It combines voice and digital network service in a single medium,. Making it possible to offer customers digital data services and voice connections through a single wire. There are two types of ISDN services, PRI (Primary Rate interface) and BRI ( Basic Rate Interface).

Connecting to the Internet Using Dialup Networking.

❖ Double click on shortcut to my connection icon in Desktop.

❖ Type the username and password in Connect To Dialog box, and click on connect button.

❖ If the Internet script file is not specified, Terminal Window will popup to accept the username and password.

❖ After the Authentication notice the user will be promoted to use the Internet.

Once the connection is established you can run any Internet related applications , Following are the important Internet Applications.

❖ Internet Browser- Browser allow you to use most internet features like sending and receiving e-mail and downloading files, Netscape Navigator and Microsoft Internet Explorer are two popular web browsers.

❖ Email programs - Used to send and receive mails, Examples, MS-Outlook and Outlook Express. Email program will help you to manage you email accounts. It is used to download and send messages using SMTP and POP3 Servers.

❖ FTP application- Used to download and upload files to FTP locations. Example: Ws-FTp, CuteFTP.

WEB BROWSERS

The web is like a vast book. Every web page contains links to other pages. Click on the links you will be connected to some other document. Web documents are written in a language called Hypertext Markup Language- HTML. HTML codes are used in conjunction with other programming languages like java and Activex. HTTP is a protocol, which is used to transmit and receive web documents . Web borrowers support not only web documents but also other internet sources like FTP, Telnet and News. Using Web Browsers you can move to a specific page by typing its address.

A URL contains the tool to be used and the internet address where the information can be found. For example URL: Http :// Eff. Org means tool is http and address is . The URL is submitted to a DNS which returns the IP address, the browser lands on the sites- i.e., the index web pages at hat site is available on your desktop. The web browser, using the URL, gets the documents you your desktop.

IF you do not know the address but you know what you are looking form you can use any web search engines such as Lycos, Web Crawler or Yahoo or Khoj.

There are a number of web browsers available now. The three most popular web browses are Netscape Navigator, Microsoft Internet Explorer and NCSA Mosaic.

Browsing the Sites using Web Browser

❖ Start your web browser. If you are using internet Explorer choose Start>Programs>Internet Explorer>Internet Explorer. When you start web browser, you automatically begin at the home page. The home page URL can be customized according to your Interest.

❖ IF you are using the Internet explorer to customize the home page, select View>Options. Internet Options Dialog box appears, Under General tab, in home page address box, type your favorite site. If you choose, Use Current button, it sets the current page as home page. IF you choose, Use Default, . Home. will be your home page. You can choose use blank, if you do not want to specify and home page.

❖ To jump to another web page, click a link. Links look like highlighted or underlined text or simple graphic icon. When the mouse cursor moves over a link. The cursor changes to a pointing finger. To god directly to specific sites type the URL of that site. Say for example you like to visit Manipal group web site, then type the URL .

HOW THE INTERNET WORKS.

In a network if you wish to send mail, enter the name of the user (i.e,, the user name to whom you wants to sent the mail.) The E-mail system of the network sends that mail to the concerned address. This arrangements is similar to calling a local telephone number. Anyone wanting to access a telephone number from outside city limit must enter the area code and the telephone number. Similarly if the two people are not in the same E-mail system, they must enter fully qualified addresses. Between these two persons there may be many networks. Once the email is sent, the message is broken into small pieces called packets. Packets are the basic unit of measurement on the Internet. There are special purpose computer called Routers on the Internet, which will deiced what is the best path to the destination to sent these packets. . Once these packets reach their path to the destination to sent these are reassemble into the original message.

The Internet has been described a cooperative anarchy. Each individual network has its own rules. Communication between networks is possible because of cooperation. There is no central administration of the Internet but there are formal bodies within the Internet that perform coordinating functions.

Routers

Routers are specialized computers that read the addresses of packets and direct the packets to their destinations. They are devices that forward traffic between networks, using information from the network layer and form routing tables. Some routers are dedicated i.e. they are used only for shuffling the traffic. Some routers are also used for other purposes including file storage. A routing table is a table or database of routing path and decision variables that allow routers to send packets on to the correct destination.

WHAT YOU CAN DO WITH THE INTERNET

❖ Search for information. IN the internet are sites that have electronic version of classic literature pages and pages of movie facts , stock quotes, collection of music and other interactive contents and mountains of additional information. Since there is awful lot of information, you may have trouble finding a place to start. There are search tools in the Internet , you may have trouble finding a place to start. These are search tools in the Internet that helps you search for specific information. Yahoo ., Hotbot , Khoj , cyber are popular search engines available.

❖ Use Electronics Mail. One of the widely used features on the internet is electronic mail. With E-mail you can send and receive mails without even leaving the keyboard . Messages can be globally just by paying local telephone charges. Email eliminates the need of postage stamps and greatly reduce the time taken to send and receive messages.

❖ Chat with other People. IF you like talking to complete strangers and making new friends, Internet is the best place. With chart programs you can chat with a group of people , whose geographical location you need not know.

HISTORY OF THE INTERNET

Internet started with the ARPA Net and a few resourceful computer scientists who wanted to share files among people working on similar projects. ARPS is the acronym for Advanced Research projects Agency of the United States Department of defense. In September 1969, the University of california, Santa Barbara and the university of Utah were connected using 500 KBps leased voice lines, and the networking is called ARPA net. Some of these networks ten connected to the ARPAnet.

Another factor in the rapid growth of this technology was the inclusion of the TCP/IP protocols in the Berkeley version of Unix. TCP/IP protocols gained wide usage, and more networks were created with them. These networks began to connect to each other. There was originally only one, the ARPAnet. Soon there were many separate networks.

As the number of networks increases every day the internet connects about 40 million users worldwide.

WORLD WIDE WEB

World wide web and the internet are not the same , but they are related and interdependent. The Web resides on top of the Internet. World Wide Web is a huge collection of pages of information lined to each other around the globe. Each pages can be a combination of text, pictures, audio clips, video clips, animations and other electronically presentable materiel. What makes web pages interesting is that they contain hyperlinsk usually called links. Each link points to another web page and when you click a link, your browser program fetches the page the link connects to. Every page can be linked to other pages anywhere in the world. This system of inter linked documents is known as hypertext.

The world Wide Web is known fondly to millions as www, W3, or simply as the Web. The Web is actually a superset of the Internet . IT can be thought of as a graphical interface to the Internet , prodding a revolutionary way of accessing information scattered across millions of computers around the world.

Before the world wide web, the internet was very difficult to navigated. Much of the information on it was tough to find and just as difficult to make use of , Locating and downloading files residing on the Internet needed some UNIX skills and specialized tools to get the job done.

As a part of his job at CERN< Bewrbers-Lee frequently used the Internet for research, collaboration and communicating with colleagues. He Knew the problems of using the Internet and was determined to make his job easier by Building a system that would make navigating easy. In 1989, he submitted a proposal for world web to the CERN Electronics and computing for physics Divisions. After receiving a feed back on the proposal he and his colleague, Robert Cailliau, revised and resubmitted it.

In February 1993 , the National center for supercomputing applications (NCSA) released the first public version of Mosaic for X-windows. It was a breakthrough software product that kicked the world wide web into high gear. It supported a user-friendly graphical user interface that appealed to people normally addition Mosaic supported the use of a mouse. You could now navigate without using your keyboard , a tremendous advance for most computer users.

Since Mosaic was introduced, the Web has skyrocketed in popularity. By April 1994, just one year after the first version was released, the web accounted for more traffic over the National Science Foundation (NSF) Backbone than Gopher, an Internet protocol.

WEB PAGES.

Familiarizing your with the Web does not take very long, and is a fun way to prepare yourself for creating Web document . The best place to start is with the web page, the visual part of a much larger system that people most often associate with world wide web. There are many components to the web just as there are many pieces to the television industry . Here, there are broadcast companies, cable itself, to name a few. The same holds true for the Web. Most people think mainly of the individual web pages , as they are the most visually captivating aspect of the entire world wide web document . A web page is much more like a word processing document than a printed page, especially, the way is viewed. When the information on a web page is not visible , you scroll either vertically or horizontally to see more.

Web site

A World Web site is simply a collection of inter linked web pages. Web pages need not be related. By its very nature, the web makes it possible to link any number of items, including other pages. For instance, a page might have links to other pages containing photography, basketball, cartoons or just about anything else. Because of the Inherent diversity found in Web, the suggest that a site is a related group of documents would be big mistake. If you were to think of the web as a giant filing cabinet, each site would be a folder inside its. The pages in turn would be documents inside the folders.

Home pages

How to find a site if it is merely a collection of inter linked pages? Simply, each site has a home page, the official accesses point into the site. From the home page, you can get an overview of the site and begin exploring it. A properly designed home page is, in essence, like a hospitable host. It is the most important page of any site, the starting point for your journey.

Web Server

The final part of the web you will need to be concerned at this point is the server. A web server does a great deal of work in making web pages and sites available to browsers. A large company may have its own server, but usually individuals and small companies rend or lease space on the server provided by an Internet Access company. Without servers there would be no web.

Web pages must reside somewhere on the Internet on order to be accessed with a browser and a server is where you will find them. There are literally millions of Web servers on the Internet , each of which may be home to thousand so web pages.

Web servers consist of special hardware and software that makes it possible to carry out browser requests. Perhaps you have heard of the term client server? Since it asks to see or use certain documents located on the internet.

Protocols

The main protocol for transferring information on the Hypertext Transfer protocol or HTTP. Web pages, both text and graphics are sent from the server to the browser using this protocol.

The web also supports most of the other popular protocols, such as File Transfer Protocol, Gopher, News and Wide Area Information Service . But you need not remember all these protocols, your browser does al the work, dynamically switching between protocols as needed.

URLS are read from left to right , just like a telephone number. The first piece of information in a URL describers what type of protocol the browser must use to retrieve a given object.

Example:

❖ http:// wais:// ftp://

❖ telnet:// file://

SEARCH ENGINES

People commonly refer to the current ear as the information Age. The best thing about today internet is the enormous range of the resources on it. The worst thing, of course , is that there is not guide to those resources. The URL of the new site must be submitted to search engine keywords are built into the index pages of the site. Submit helps you submit your URL to these search engines. Some search engines have a definite format and expect you to type the keywords again, while other just require the URL. The search engine displays a list of locations that matches your search parameters.

Popular Search Engines

❖ - This is one of the earliest and very popular engines, Yahoo is a preferred choice for millions surfers.

❖ -An effective tool to pinpoint the site of your choice. Carnage Mellon University developed this site.

❖ - By far, one of the most effective search engines that will search the world wide web for the information you need. A good feature is the search within results which will narrow down the results to a manageable number of web sites.

❖ - The exciting thing about this engine is the profusion of chat links ranging from the general to the very specific.

❖ - The search options are a hunters delight. You can search in terms of words, language and time.

❖ - It is the mother of all searches, because six engines do the work for you at once.

❖ - Their daily toolbox is an interesting add on that lends it an extra edge.

❖ - Elegant in it simplicity, this engine does the job efficiently.

❖ - a search engine for Indian web sites. The Kjoh home page has links to topics of Indian interest.

HELPER APPLICATIONS

Your web browser may not be able to play some type of files directly. It can automatically run a helper application that can play the file. Helper applications are small programs that typically run very quickly and require little memory.

Whenever your web browser encounters a file it cannot play, it copies the file to your computer and urns the helper application. The application is used to automatically open the file and play it or display it on the screen. The helper programs are also known as plug-in programs.

Popular Plug-ins

❖ Real Player: Plays sound files as you download them. Micro-soft Netshow does much the same thing.

❖ Quick time: Plays video files and VDOLive, which plays video as you download them.

❖ Shockwave: Plays both audio and video files in addition to other types of animation.

❖ Ichat, ICQ: Lets you use your Web browser to participate in online chats ICP is a very popular chat program.

INTERNET RELAY CHAT (IRC)

Joining the chart room in World Wide Web is something similar to a conference call except that rather than talk. You type on your keyboard . You can see what other people are talking on Screen. Although all the people participating in the chat can be typing at one time, each person's contribution is presented on-screen in order of its receipt, identified by the name of the person who typed it. You can chat in two main ways:

❖ Channels or Rooms: Resembles an ongoing conference call with a bunch of people. After you join a room, you can read on-screen what people say and then add your own comments just by typing them and press enter.

❖ Direct connection : A private conversation between you and another person connected to the chat portion of the internet. There are popular web sites like where you can join the chat room you can joint to a specific chat room and chat with many people. To join few chat rooms you must download some and software. MIRC and ICQ are the popular chat software . There is a java applet in chat pages which will allow you to chat with specific individual or a group of people.

Chatting-Code of Behavior

❖ Chatting is not to hurt anyone. A real person with real feeling is at the other end of the computer chat connection.

❖ Be cautious. You really have no idea who that other person is.

❖ Keep your messages short and to the point.

❖ Don not insult people and do not use foul language.

❖ IF you want to talk to some one in private , send that person a message saying hi, who you are and what you want.

❖ IF the tone of conversation in one chat room offends you, then you can always leave.

Safe Chatting Rules

Here are some guide lines for conducting safe and healthy chats:

❖ Many people in chat groups lie about their occupation, age, locality and gender. Some think that they are just being cute, some are exploring their own fantasies and some are troublemakers.

❖ Be careful about revealing information that enable some one to find you, or find where you live or work or your phone number . This information includes your last name, phone number, mailing address and schools you kids attend.

❖ Never give out your passwords to any one. If you chart service offers profiles and a person without a profile wants to chart with you, be extra cautious.

TELNET

People who are in one location frequently want to use a computer in another location. Perhaps they are on a business trip and wants to read their e-mail Perhaps they want to access data on the computer in another branch or in the main office.

You can also use Telnet to get services, such Gophers, line mode web service and libraries, even if you do not have clients for those servers on your system. Telnet , you interact with that computer and operating system and issue commands as if you were directly . Telnet provides a command line interface internet hosts running the Telnet service. With Telnet , you can establish a remote session with an internet host. Telnet is useful for the remote administration, internet hosts over the Internet.

Using Telnet

Telnet is one of the simplest tools on the internet. To open a line mode session with remote host from a system prompt, type :telnet hostname

You should see the welcome or login banner for the host. When the Telnet program connects your computer to the remote computer, remote computer usually asks you to enter a username and password.

Some Telnet sites require that you type commands at the prompt. In such cases instructions appear at the bottom of the screen telling you what to type. If the instructions do not appear, you can often view a list of commands or instructions by type help or ? at the prompt and pressing Enter.

Windows Telnet Program

You can use windows Telnet program to connect to remote telnet site after connecting to the Internet. To connect to remote site select connect remote system. It will ask you the host name. Type any Telnet address.

Telnet Sites

❖ Argone National Laboratory in lllinois offers an educational service called Newton. To reach it, Telnet to newton.dep.

❖ IF you need agricultural information , try cornell's Extension Network. To reach CENET, Telnet to empire .cce. cornell. Edu.

❖ There is a backgammon server at fraggle 165.mdstd. chalmers.se

❖ To vanderbit. You can play bridge by Telnetting

❖ Telnet to to find a bulletin board system (BBS) that is the bookstore Book Stacks Unlimited.

❖ Telnet to pac. to find book reviews and a journal article fax service.

❖ Telnet to classroom-earth. 2010 to find the Global change education bulletin board.

FTP (FILE TRANSFER PROTOCOL) APPLICATIONS

Transferring a file via FTP requires two participants: an FTP Client program and FTP server program. The FTP client is the program that we run on our computers. The FTP server is the program that runs on the huge mainframes on a PC under someone desk. The FTP client can download or upload files to the FTP server.

Using Web browser you can download the files but you can not upload the files FTP applications will help you to upload the files to the web sites, By typing open command you can connect to any ftp server. To connect to FTP server you must have a login name and the password . Most of the FTP servers allow anonymous connections . In this case username is anonymous and password is you e-mail address. To upload the files you can use mput command. To list the available commands you can type help.

Another important FTP program, which is available as a shareware, is WSFTP, Using this windows based program if is easier to maintain your web site.

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