Internet and E-mail (English) 02 - සාමාන්‍යපෙළ තොරතුරු හා සන්නිවේදන තාක්ෂණය

Internet and E-mail (English) 02

Classification of computer Networks

According to the geographical pattern of composition a computer network is classified as LAN, MAN, and WAN.


LAN - Local Area Network

A local area network (LAN) is the basic building block of any computer network. A LAN can range from simple (two computers connected by a cable) to complex (hundreds of connected computers and peripherals throughout a major corporation).

– The distinguishing feature of a LAN is that it is confined to a limited geographic area.

This is the simplest form of network used widely. LANs are set and fixed in smaller building. The transmission media used for LANs are telephone lines, coaxial cables and fiber optic cables.


MAN - Metropolitan Area Network

This is computer network covering a reasonable wide geographical area. Branches of a company spread out through a wider metropolitan area is an example for usage of a MAN. These networks are bigger than LAN's and they have lot of computer resources because more computers are linked. The transmission media used is Fiber optic.


WAN - Wide Area Network

WAN is a massive computer network. WANs can cover a bigger area, as spread throughout the world. In addition to normal transmission media Microwave relays and satellite are used. WAN as a whole is a computer network consisting of other computer networks. A WAN has lots of LANs and MANs in it. WAN computer networking is important in International communications. The Internet is the world's biggest computer network with limitless resources, and this can be called a WAN.


The Internet

The internet was originally conceiver, designed, and implemented in the 1960s as a United States Defense Department strategy of protect lines of communications and access to vital databases in the event of nuclear attack.  The early version of the Internet, called Arpanet, connected computer in military installations and universities in the United States; this network was then expanded to Canada and Western Europe.  It was only in the 1990s, however, that the Internet moved out of university research centers and into the homes and business of millions of people around the world.  This phenomenon is the result of the World Wide Web (www) an amazing development that transformed a boring, text-based communication system into a dynamic, colorful, multimedia-rich environment.


One of the strength of the Internet has always been that it is platform-independent: regardless of the type of computer and O/S you have, you can connect to the Internet.  This means that a Macintosh user living in Great Britain can post information on a computer in London that runs the WIN NT O/S, have that computer connect to the computer connect to the computer in London and receive the information they need.  In a matter of seconds, information is literally transported halfway around the world.


Of course, the original designers of the Internet did not envision2 the innumerable3 uses that people of the 90s have found for this incredible communications tool.  but the need to make any sort of file available to remote users, regardless of which computer they use, is exactly why the Internet was created.