ComputerNetworks

What is computer Networks?
A computer networks is an interconnection  of various nods  , located at different places , but connected with each other via a communication links or channel me be wireless or wired connection. the main purpose of computer networks is to share recourse between each other.
 Node?
Network devices are called Node. A node can be any computer , printer are any other end devices which is capable of sending or receiving information through interconnected devices.
History of Computer Networks?
First of all in 1962 two computer are interconnected with each other successfully , After this by the help of USDoD four computer are interconnected with each other. The name of this project is ARPANet .
USDoD stand for United State Department of Defense.
ARPANet stsnd For Advance Research Project Agency.

1. UCLA, stand for University of California at Los Angles
2. UC Santa barbara 
3. Stonford research institute (SRI)
4. Uni of Utah

The communication between this four uni is called ARPANet,  Then in 1972 thirty nodes are interconnected successfully and in 1980's its extension is up to Europe via satellite and finally in 1990's Internet come to being officially for public every where in the world.
What do you mean by classification of computer networks?

1.   Based on the Transmission mode: 

it define direction of data flow.
their are three mode of data flow define shortly as under

• Simplex: its uni-directional means the data can send only in one direction. e.g Use in printer etc
• Half Duplex: Bi-directional means the data can send on both direction but not at a time (only one can send data at a time)
• Full Duplex: By directional means send and receive data on both direction at a time.

      2.   Based on Time in Transmission:

• Synchronous time transmission: 
• Asynchronous time transmission:

      3.   Based on Authentication:

• peer to peer Networks: In peer to peer networks one computer can send the request and full fill the request e.g Bit Tarrent 
• client Server Networks: The client can send request only and full fill the request is the responsibility of Server.

      4.  Based on Geographical   location:

• LAN: Local area networks use in Building, organization. 
• MAN: Metropolitan area networks use i same city between two or more building of same organization e.g two are more branches of one college in one city. 
• WAN: Wide area network use all over the world e.g internet.
• CAM: campus area network use in small campus, school ect.
• HAN:Home area network use in home , shop.

      5.   Based on Reliability:

• connection oriented: Establish a session connection between sender and receiver before communication e.g TCP stand for Transmission control protocol. 
• Connection less communication: No session connection is establish before communication e.g UDP stand for User Data gram Protocol