Basics in Internet

Introduction

It seems like everyone's talking about the Internet these days. But what is itreally? How does it work? How do you access it? And most important, what can it do for you at work or at home? Fortunately, accessing and using the Internet is fairly simple. Let this tutorial be your guide to the Internet as you connect for the first time and explore the network's vast and useful resources. The Internet is a worldwide collection of computer networks, cooperating with each other to exchange data using a common software standard. Through telephone wires and satellite links, Internet users can share information in a variety of forms.

What is internet?

The Internet is a global collection of people, who are linked through computer cables and telephone lines, making communication possible with each other in a common language for specific purposes. However, the rigid technological definition of Internet is that it is a global connection of interconnected networks. By definition, a network allows computer users to share computer equipment, programs, message, and information available at one site. The earlier attempts in computer networks were limited to Local Area Networks and Wide Area Networks. Internet is defined as network of networks; that is, it connects many LANs and WANs. Figure 1 depicts the Internet. There are a many major networks participating in the Internet is not the only global network available. Some of the commercial networks such as CompuServe (CIS) and MCI Mail and America Online are also global networks. These global networks a re owned by different agencies that charge user for access.

How does internet Works ?

A computer network, by definition, allows sharing of resources. One such major resource is information, which exists in computers in the form of files of data. Thus, one of the key aspects in network of many computers is to move the files between tow specific computers. For such a communication, we require:

• the address of the destination
• a safe method of moving data in the form of electronic signals.

As far as safe movement of data is concerned, there exist a set of rules, which governs sending and receiving of data on the Internet. These rules are implemented in tow parts in the network software and are called Transmission Control Protocol (TCP) and Internet Protocol (IP). These tow are collectively called TCP/IP. For sending a large block of text/data to another machine, TCP divides the data into little data packets. It also adds special information e.g. the packet position in the document, error correction code etc. to make sure that these packets, at the destination, can be reassembled correctly, without any damage to data. The role of IP here is to put destination-address information on such packets.
On Internet it is not necessary that all the packets follow the same path from source to destination. A special machine called "router" tries to load balance various paths that exists on the network.
Another special hardware/software called gateway allows different electronic networks to talk to internet which uses TC/IP (refer to Figure 2.) As an Internet user one may not be interested in knowing how messages are converted to packets, but one must know how address are to be given. Let us explore the addressing mechanism on Internet in more details.

Domain Name System (DNS)
Address are essential for virtually everything we do on the Internet. The IP in TCP/IP is a mechanism for providing addresses for computers on the Internet. Internet address have tow forms:

• person understandable which are expressed as works
• machine understandable that are expressed as numbers also called IP addresses

username@host.subdomain.domain

Hosts are, in general, machines at a particular location. Resources. Resources of a host machine are normally shared and can be utilized by many users on the Internet. A user is given an account by system administrator, which allows him to use the resources of the machine.
The username in general, is the name of your Internet account for logging into the host machine. Logging in is the process of gaining access to your account on a computer, which is shared by several users.
Hosts and local networks are grouped together into domains, which are grouped into one or more larger domains. For an analogy a host computer is considered as an apartment building in a housing complex and your account is just an apartment in it. Domain may be an apartment complex, town, or even a country.
Sub-domains may correspond to organizations such as NASA or CompuServe. Domains are classified as non-geographic and geographic figure 3 list various common domain names. The domain names in India come under a larger domain "in".

Non-Geographic domains
.com = commercials organisations
.net = network organisations
.gov = parts of governments
.edu = organisations of higher education
.mil = non-classified military networks
.org = organisations that do not fit the commercial or educational designation

Few Geographic Domains

AUSTRALIA = .au
CHINA = .cu
GERMANY = .de
INDIA = .in
JAPAN = .jp
UNITED KINGDOM = .uk
UNITED STATES = .us

Nepal = .np

The Internet address socis@del2.vsnl.net.in indicates that the host computer whose name is del2 is one of the host computer in the sub-domain named Videsh Sanchar Nigam Limited (vsnl) which is a network organisation (net) and is situated in country India (.in). The socis is one the user group in this server/host (del2).

IP Address:

IP Address: as stated earlier, these are machine understandable addresses. The IP address of a host computer (also called a server) is termed as host address. Significance of IP addresses for computers are same as significance of telephone numbers to us.>
An IP Address consists of four sets of numbers that are separated by dots. These addresses are organized from left to right. The del2 server of VSNL has an IP address 202.54.15.30. A portion of number separated by the dot is known as an Octect, that is, 8 bits of information. Thus, IP addresses have four octets that are equal to 32 bits. Just like our telephone numbers which include country code, city code, exchange code and the user code, the IP addresses consist of sequence of domain code and sub-domain code from left to right.
Computers termed as name servers contain databases of Internet host addresses. They translate word addresses or person understandable addresses into numeric equivalents.

Who governs The internet?

Internet has no president or chief operating officer and is governed by a number of authorities. The ultimate authority of Internet rests with Internet Society (ISOC) a voluntary membership organisation. The purpose of this organisation is to promote global interchange of information. Another authority is a group of invited volunteers called-Internet Architecture Board (IAB). The IAB sets standard and gives Internet addresses. Internet Engineering Task Force (IETF) discusses the technical and operational problems on Internet.
Who pays for it?
No one pays for using Internet; instead everyone pays for its part.