Computer Networks Notes for GATE exam

Hello folks, Hope you all are doing good. I am going  to share my GATE notes, which I have prepared during my preparation. I am starting with Computer networks and hoping that it will help you. In Part-1 and some next parts, I will share  notes about Introduction, So keep checking my upcoming blogs. So lets start with fundamentals,

Network Definiton :

  1. Network is a collection of interconnected nodes.
  2. Interconnection can be logical or physical.
  3. without interconnection resource sharing is not possible.

Characterstics of a network :

Every network has the following 3 characterstics,

  1. Size
  2. Type
  3. Accuracy


  1. Small : A network which occupy less amount of space and contains less number of nodes.
  2. large : More amount of space and contains more nodes.

Note : 

  • Personal area network is smallest network just having 2 nodes with respect to nodes like pc and printer, but with respect to occupancy is bluetooth.
  • Inetrnet is largest network.wrt to occupancy and nodes.


There are basic two types of networks

  1. Connection-Oriented : For exa[mple telephone network [connection establishment -> Data transmission -> Connection release]
  2. Connection-less : For example mobile network [dont have connection establishment and  Connection release ]

Note :  Internet comes under both connection-oriented and connection-less

Accuracy [efficiency]

  1. Efficient n/w : All conection oriented network comes under efficient network.
  2. Inefficient n/w : All connection less network comes under inefficient network.

Efficiency/ effectiveness of a network

Efficiency of network is depends upon following parameters:

  1. Delivery: If the intended receiver recieve the correct message or not. [ successful transmission ]
  2. Accuracy: If the message send to the receiver without any modification or violation.
  3. Timeliness: If the message reach to receiver within the time or not.
  4. Jitter:
    • Which can be define as amount of variance in packet arrival.

    • In networking, Jitter refers to small intermittent delays during data transfers. It can be caused by a number of factors including network congestion, collisions, and signal interference.

Block diagram

In block diagram there are 5 most important part exists :

  1. Sender : Sends and generates the message.
  2. Receiver : Receives and processes the message.
  3. Meduim [transmission medium] : Which is used for communication between sender and receiver.
  4. Message : Plain text, It is the information which the sender willing to transfer to receiver.
  5. Protocol : Set of rules that governs the data transmisson b/w sender and receiver.

Type of protocols

  1. Connection-Oriented Protocol : A protocol which requires the ce[connection establishment]after the dt [data transmission] and cr [ Connention release ].
  2. Connection-less protocol : No connection establishment and releasing required.

Computer network

A collection of interconnected autonomous[independent] computers

  1. Wired network - In wired network nodes have behaviour of autonomous
  2. Wireless network - In wireless network nodes can be autonomous as well as mobility [even though a node is moving but still transmitting data ]

Applications of Computer Networks

  1. Reliability : Always gives guarantee of success data transmission using alternate link when there is error occur.
  2. Scalability : which allows network size can be increased.
  3. Resource sharing and Saving money : If there is need to connect four printers to the  system amd if there is no way to implement the computer network then it will be more expensive because four computers will have four printers separately but if network is available then one printer is used buy all system and will be cheaper.
  4. People : entertainment, communication, remote info accessing
This is the Part-1 and I hope this would be helpful for you. In case, If you any doubt/query you can drop in comment section.

Have a Bright future !