NOS : Certificate in Computer Applications
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33
Fundamentals of Internet
33.1 INTRODUCTION
The latest buzzword in computer world is ‘Internet’. It has taken the entire world by surprise with its cutting edge technology to connect people and computers throughout the world. Using Internet, organizations all over the world can exchange data, people can communicate with each other in a faster and effective way, and researchers can gather information in their respective area of research. With help of video conferencing over Internet, it has become possible that people can even see each other while communicating and it is possible by video conferencing over Internet. Even one can do all his shopping sitting back at home. He does not bother to go to the crowded market place. Slowly shopkeepers are also opting for electronic commerce, which provides them greater reach and fastest way to do business over Internet. Don’t get surprised, if you come to know that the Paanwalla in your locality has started selling his paan over Internet.
33.2 OBJECTIVES
At the end of this lesson you would be able to:
33.3 Internet- The History?
In 1969, the U.S. Defence Department funded a project to develop a network, which can withstand the bombing. Basically the idea was to develop a very secure network which can work even after a nuclear attack. This project was known as ARPANET. The proposed network was not supposed to have a central control—which would be an obvious target. Ten years of research brought Local Area Ethernet Networks (LANs) and workstations were developed to get connected to LAN. These workstations and LANs were then connected to the ARPANET. For next decade the ARPANET grew and its decentralized features helped its rapid expansion. Computers connected to ARPANET used a standard or rule to communicate with each other. This standard used by ARPANET is known as NCP (National Control Protocol). Protocol is a network term used to indicate the standard used by a network for communication. But the passing time and rapid change in information technology suppressed NCP and brought TCP/IP (Transmission Control Protocol/Internet Protocol) in to the world of networking. TCP "converts messages into streams of packets at the source, and they are reassembled back into messages at the destination. IP handles the dispatch of these packets. It handles the addressing, and makes sure that a packet reaches its destination through multiple nodes and even across multiple networks with multiple standards. This flexibility of TCP/IP to handle multiple networks with multiple protocols encourages other networks to get connected to ARPANET. Slowly the ARPANET became a massive network of networks and now it is known as ‘Internet’.
Internet is termed by some people as the world of largest democracy with no government. It has no state of head to control it.
Why do people want to get connected to Internet? May be because of freedom it provides. The Internet is a rare example of a large democracy with no state of head, no official censors, no bosses, no board of directors. Nobody controls the Internet and in principle, any computer can speak to any other computer, as long as it obeys the technical rules of the TCP/IP protocol. This freedom of Internet helped it to move out of its original base in military and research institutions, into elementary and high schools, colleges, public libraries, commercial sectors even into the shop of a vegetable vendor.
33.4 Services of Internet - E-mail, FTP, Telnet, WWW
But what does one do with the Internet? May be four things, basically: mail, discussion groups, long-distance computing, and file transfers. Internet mail is (e-mail or electronic mail), much faster as compared to normal postal mail. One can also send software and certain forms of compressed digital image as an attachment. News groups or discussion groups facilitate Internet user to join for various kinds of debate, discussion and new sharing. Long-distance computing was an original inspiration for development of ARPANET and does still provide a very useful service on Internet. Programmers can maintain accounts on distant, powerful computers, execute programs. File transfers service allows Internet users to access remote machines and retrieve programs, data or text.
(a) E-Mail (Electronic Mail)
E-mail or Electronic mail is a paperless method of sending messages, notes or letters from one person to another or even many people at the same time via the Internet. E-mail is very fast compared to the normal post. E-mail messages usually take only few seconds to arrive at their destination. One can send messages anytime of the day or night and it will get delivered immediately. You need not to wait for the post office to open and you don’t have to get worried about holidays. It works 24 hours a day, seven days a week. What’s more, the copy of the message you have sent will be available whenever you want to look at it - even in the middle of the night. You have the privilege of sending something extra even such as a file, graphics, images etc. along with your e-mail. The biggest advantage to using e-mail is that it is cheap, especially when sending messages to other states or countries and at the same time it can be delivered to a number of people around the world.
Although e-mail is faster and cheaper, it has many of the components of regular mail. It allows you to compose note, get the address of the recipient and send it. Once the mail is received and read, it can be forwarded, replied. One can even store it for later use, or delete. In e-mail even the sender can request for delivery receipt and read receipt from the recipient.
(i) Features of E-mail:
(ii) Components of an E-mail Address
As in the case of normal mail system, e-mail is also based upon the concept of a recipient address. The email address provides all of the information required to get a message to the recipient from anywhere in the world. Consider the e-mail ID
john@hotmail.com
In the example above, "john" is the local part, which is the name of a mailbox on the destination computer, where finally the mail will be delivered. Hotmail is the mailserver where the mailbox "john" exists, .com is the type of organisation on net, which is hosting the mail server.
There are six main categories;
com Commercial institutions or organization
edu Educational institutions
gov Government site
mil Military site
net Gateways and administrative hosts
org Private organizations
(b) FTP (File Transfer Protocol)
File Transfer Protocol, is an Internet utility software used to upload and download files. It gives access to directories or folders on remote computers and allows software, data and text files to be transferred between different kinds of computers. FTP works on the basis of same principle as that of Client/Server. FTP "Client" is a program running on the your computer that enables you to talk to, and get stuff from, remote computers. The FTP client takes FTP commands and sends them as requests for information from the remote computer or known as FTP servers. To access remote FTP server it is required but not necessary to have an account in the FTP server. When the FTP client gets connected, FTP server asks for the identification in-terms of User Login name and password of the FTP client. If one does not have an account in the remote FTP server, still he can connect to the server using anonymous login.
Using anonymous login anyone can login in to a FTP server and can access public file archives, anywhere in the world, without having an account. One can easily Login to the FTP site with the username anonymous and e-mail address as password.
The basic objectives of FTP are
The basic steps in an FTP session are:
(c) Telnet (Remote Computing)
Telnet or remote computing is telecommunication utility software, which uses available telecommunication facility and allows you to become a user on a remote computer. Once you gain access to the remote computer, you can use it for the intended purpose. The TELNET works in a very step by step procedure. The commands typed on the client computer are sent to the local Internet Service Provider (ISP), and then from the ISP to the remote computer that you have gained access. Most of the ISP provides facility to TELNET into your own account from another city and check your e-mail while you are travelling or away on business.
The followings steps are required for a TELNET session
In-Text Question 33.1
1. Fill in the blanks.
(a) _______ is a network term used to indicate the standard used by a network for communication.
(b) File Transfer Protocol, is a __________software used to upload and download files.
(c) Hotmail is the___________.
(d) The commands typed on the client computer are sent to the _______________.
(e) The basic objective of FTP are to give flexibility and promote sharing of files and____________.
33.5 WORLD WIDE WEB (WWW)
WWW is the acronym for the World Wide Web. It is also commonly known as ‘The Web’. The WWW is hypertext based information retrieval tool. One can easily surf the Web by jumping from one document to another using the links in those documents. These documents can be in many formats, such as text, graphics, animation, sound and latest is video. They may also be a combination of all these. All the information on Internet are presented to the user as a document or more popularly known as Web Page. All these Web Pages are link to each other or even to section within a Web Page. And these links are known as Hyper Links.
The tool used to view these Web Pages on Internet is known as Internet browser or simply browser. It is a software program specifically developed to extract information on user request from the Internet and present them as a Web Page to the viewer. There are several browsers available in the market. However the most popular are Internet Explorer from Microsoft and Netscape from Netscape Inc. The process of using browser to view information on Internet is known as Browsing or Surfing.
Fig. 33.2
(a) Internet Address
Just like every house, every office, every location has an address, every page on the Internet has a unique address. This address is used get the web page for user from Internet.
Just as the address of a house or office is known as its postal address, the address on the Internet is known as URL (Uniform Resource Locator). A typical Internet address or URL would look like;
http://www.nos.org/computers/internet/url.htm
The URL locates a particular web Page, among all the computers connected to the Internet. The URL contains the components that specify the protocol, server, and pathname of an item. Let us examine the URL given above (http://www.nos.org/computers/internet/url.htm).
The protocol is followed by a colon (http:), the server is preceded by two slashes (//www.nos.org), and each segment of the pathname is preceded by a single slash (/computers/internet/url.htm). A protocol is set of rules that tells the computer know how to interpret the information at that address.
Fig. 33.3
The first component, the protocol, defines the manner for interpreting computer information. Many Internet pages use HTTP (HyperText Transfer Protocol). Other common Internet protocols that one might come across are FTP (File Transfer Protocol), NEWS (Usenet news groups protocol), and GOPHER (an alternative transfer protocol). Gopher protocol is mostly out of date now.
The second component, the server (www.nos.edu), identifies the computer system that stores the information you seek and is always preceded by two slashes. A server is a computer that has information stored on it and sends it to the client, when a request is made. Each server on the Internet has a unique address name whose text refers to the organization maintaining the server.
The last component (/computers/internet/), defines the path within the Server where the requested item (url.htm) will be found. Most of the Web pages will have .htm or .html as their secondary or extension name.
(b) How to get connected to Internet
There are various type of connectivity to get hook on to Internet. They all can be broadly classified into following category.
Gateway Access is also known as Level-One connection. It is the access to the Internet from a network, which is not on the Internet. The gateway allows the two different types of networks to "talk" to each other. But the users of the Gateway Internet have limited access to the Internet. They might not be able to use all the tools available on Internet. The local Internet Service Provider (ISP) normally defines this limitation.
Good example of network with Level One connectivity within India is that of VSNL (Videsh Sanchar Nigam Limited). All access to Internet from India are through VSNL gateway.
Fig. 33.4
(ii) Dial-up Connection
‘Dial-up’ connection is also known as Level Two connection. This provides connection to Internet through a dial-up terminal connection. The computer, which provides Internet access is known as ‘Host’ and the computer that receives the access, is ‘Client’ or ‘Terminal’. The client computer uses modem to access a "host" and acts as if it is a terminal directly connected to that host. So this type of connection is also known as ‘Remote Modem Access’ connection. And the host to which the client gets connected is actually connected to the Internet by a full time connection (See Leased Connection).
Fig. 33.5
In dial-up connection to Internet, Host carries all the command that are typed on a client machine and forward them to Internet. It also receives the data or information from the Internet on behalf of the ‘Client’ and passes it to them. The client computer acts as a ‘dumb’ terminal connected to remote host.
This type of connection can further be divided into two categories.
(iii) Shell Connection
In this type of Internet Connection, the user will get only textual matter of a Web Page. This connection does not support Graphics display. However the user will be able to surf the Internet, do FTP, receive mail. Shell Accounts were the only type of Internet access available for many years before the Internet entered in to the world of graphics and became more users friendly.
(iv) TCP/IP Connection
Today’s graphical World Wide Web browsers provide easier access with multimedia sound and pictures. The major difference between Shell and TCP/IP account is that, Shell account can only display text and does not support graphics display, whereas TCP/IP can display both. Hence it is more popular Internet connection. Shell accounts are slowly phasing out from the Internet scenario.
To access any of these dial-up accounts you need the followings;
(v) Leased Connection
Leased connection is also known as direct Internet access or Level Three connection. It is the secure, dedicated and most expensive, level of Internet connection. With leased connection, your computer is dedicatedly and directly connected to the Internet using high-speed transmission lines. It is on-line twenty-four hours a day, seven days a week. Leased Internet connections are limited to large corporations and universities who could afford the cost.
In-Text Question 33.2
1. State whether the following statements are True or False.
(a) WWW is the acronym for the World Wide Web.
(b) In TCP/IP connection, the user will get only textual matter of a Web Page.
(c) Gateway Access is also known as Level-One connection.
(d) Good example of network with Level One connectivity within India is that of VSNL
(e) E-mail is known as URL (Uniform Resource Locator).
(f) Leased connection is also known as direct Internet access or Level Three connection.
33.6 WHAT YOU HAVE LEARNT
In this lesson you learnt the history of Internet. Also you learnt the various types of services provided by Internet .In the process you could understand the concept of e-mail and file transfer protocol. By now you should be in a position to access Internet and put it to various uses.
33.7 TERMINAL QUESTIONS
1. Explain in brief the concept of e-mail.
2. What are the basic objectives of FTP?
3. What is the difference between Leased connection and Dialup connection?
4. Explain in brief
(a) TCP/IP connection
(b) Telnet
(c) Gateway Access
(d) Shell connection
33.8 FEEDBACK TO IN-TEXT QUESTIONS
In-Text Question 33.1
1.
(a) protocol
(b) internet utility
(c) mailserver
(d) local internet service provider
(e) data
In-Text Question 33.2
1. (a) True (b) False (c) True (d) True (e) False (f) True