IBPS SO IT Officer Computer Networking Notes


Jan 30 • Bank, IBPS Specialist Officer • 4021 Views • No Comments on IBPS SO IT OFFICER COMPUTER NETWORKING NOTES


Twisted pair cable

It contains two conductors that are separately insulated and twisted.

Two types of twisted pair cable

UTP (un-shielded twisted pair cable): It is used in telephone network, office etc. it is prone to noise and interference. 2 pair cable use RJ-11 connector and 4 pair cable use RJ-45 connector.

STP (shielded twisted pair cable)It is shielded with copper braid jacket and a foil is wrap between and around the wire. It is less prone to noise and interference.


  1. Flexible
  2. Cheap
  3. High speed with 100 m limit.


  1. Low bandwidth
  2. Less protection

Wireless transmission

Earth’s atmosphere is used as a transmission medium instead of wires. It is used when connection through wires is not possible or feasible.

Wireless transmission techniques are as follows:

Radio Waves : Having frequency range of 3 Khz-1Ghz. These are omnidirectional and have low frequency so penetrate through walls and prone to interference.



These are unidirectional and range from 1 to 300 Ghz. These are highly dependent on weather conditions and travel in straight direction.


Used by cellular phones, satellite, wireless LAN.


Use infrared light for transmission. Frequency range from 300 GHZ TO 400 GHZ. It provide high bandwidth and high data rate. Used for short-range communication. Cannot pass through walls.

Used in PC’s, mobile phones.

Satellite communication

Satellite communication use microwave transmission system. Satellite placed at 3600 km above the equator where its orbit speed exactly matches the earth’s rotation speed. Data transfer rate are 1 to 10 Mbps.  especially used for remote locations.

Network architecture


Ethernet  is  a physical layer LAN technology.  It is an ideal networking technology for all computer. IEEE standard for Ethernet is 802.3.


  1. Good balance between speed , cost and ease of installation.
  2. Support all virtual networks.
  3. Define rule for configuring an Ethernet network.

Fast Ethernet

It needs higher transmission speeds. IEEE 802.3u define fast Ethernet standard. Speed limit rm 10 Mbps to 100 Mbps.

Types of fast Ethernet

100BASE-T4 , 100BASE-TX, 100BASE-FX

100BASE-TX standard popular due to its close compatibility. With 100BASE-T.

Token ring

802.5 IEEE standard is called token ring. It consist of collection of rings connected with end to end point of rings.  


Data is transmitted in tokens, which is passed along the ring. User can free token by removing the token.


Fiber distributed data interface is a standard for data transmission on fiber optic lines in local area network. Range up to 200km. This is based on token ring. Support thousand of users.   

NIC (Network Interface Card) It works on physical as well as Data link layer due to its dual functionality. NIC of a system is a place where its MAC address is stored. The NIC is built into motherboard of the system. This ensures each system in a network has different MAC address due to different NIC on different system.


Simultaneous transmission of multiple signals.

Type of multiplexing

  1. Frequency division multiplexing : It is an analog technique applied when bandwidth of a link greater.
  2. Time division multiplexing : It allow several connection of high bandwidth signals.

IP addressing

Internet protocol is a unique address for node to node connection. It is 32 bit address represented as 4 decimal values. Range of an IP address is 0 to 255.  Also known as “dotted decimal” notation. Local machine address is

Example :

Address classes

Class A           1 to 127 decimal

Class B           128 to 191 decimal

Class C            192 to 223 decimal

Class D           224 to 239 decimal

Class E            240 to 254 decimal


Default subnet mask

Class A-

Class B-

Class C-

CIDR- Classless inter domain

 Ping : used to check for a response from another computer on the network. It tells the status of computer on network.

Error detection and correction

Data can be corrupted during transmission


Types of errors

Single bit error: change in only one bit of data. From 0 to 1 or from 1 to 0.


Burst error : two or more bit are changed from 0 to 1 or 1 to 0.


Flow control : data sent from one host to another by a single medium.

Stop and wait: 


Sender send the data to stop and wait until the acknowledgement is received.


If an error is detected in any frame or acknowledgment is lost then sending station re-transmit the same frame until it is received error free.


It is basic transfer unit associated with packet-switched network. Data-gram have header and payload section. It provide a connection-less service.


Means data received exactly like it was send. No change in data.

Four techniques are used to check integrity.

  1. Simple parity check: after adding a redundant bit total data units are become even number of 1’s.
  2. Even parity bit : A parity generator is append before transmission of data. Parity generator count number of 1’s and append parity bit at end. If parity bit is even then whole unit is rejected.
  3. Cyclic redundancy check : The receiver side calculates the proper parity character from received block of data. Calculated parity is compared with that sent in character check field. If both are same then no error. If not then indicate the error.
  4. Checksum : If parity bit leaves same error undetected then parity bits of all the character in frame check for error detection.

Hamming code:  Used for detecting two error or correcting a single error.
Different Topology of Networks

Bus Topology-

  • In Bus topology, different nodes within a network are connected  together through a common linear bus(cable).
  • In this topology, transmission mode is half duplex means communicating devices can be sender or receiver both but can send data only one at a time.


  • Easy to connect a computer or other peripheral devices.
  • Less Expensive.
  • Works well in small area.
  • Entire network gets shut down if there is break in main cable.
  • Large amount of packets, collisions the network which may leads to high amount of packets loss.
  • Easy to understand
  • Easy to expand
  • Slower than ring topology

Star Topology-

  • In Star Topology, All nodes within the network are connected to the central node which work as a hub or switch for all nodes.
  • More Expensive due to usage of large number of cables.
  • If one cable breaks down then only one node will not work and other nodes will work as they are working before.
  • It is normally connected with bus topology to make a hybrid network.
  • Hub acts as a repeater for flow of data
  • Easy to Setup, Modify and troubleshoot
  • Installation cost is high


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Ring Topology-

  • In Ring topology each node is connected with two other nodes within the same network.
  • This topology used large number of Repeaters.
  • The transmission is unidirectional but it can be made bidirectional using two cables.
  • Installation cost is low.
  • Easy to Expand.
  • In this topology data is transferred serially one bit at a time.
  • Troubleshooting is difficult
  • Failure one computer disturb the whole network.
  • Deleting or adding nodes, cause the disturbance in the network activity


Mesh Topology-  In Mesh topology a single node is connected with all other nodes available in the same network.

  • There are two techniques to transmit  data over the network.
  1. Flooding
  2. Routing
  • There are two types of Mesh topology
  1. Partial Mesh topology
  2. Fully Mesh topology
  • It is robust.
  • Not Flexible
  • Fault can be identified easily.
  • Provides Privacy and Security.
  • Most Expensive
  • Cabling cost is more.
  • Installation and Configuration is difficult.


Tree Topology-

  • In this topology, there is one root node and all other nodes connected to it in the form of hierarchy . that’s why it is also called as Hierarchical topology.
  • Used in Wide area network.
  • If root nodes fails then entire networks fails.
  • Costly
  • Maintenance is difficult.
  • Addition of nodes is easy


Hybrid Topology –

  • It is a combination of two or more topologies.
  • Inherits the advantage and disadvantage of the topologies that is included in the network.
  • It is Flexible.
  • Reliable as error detecting is easy.
  • Costly
  • Complex in design
  • Size can be increased easily.
  • Effective


Resource-  Resource can be any hardware device i.e. Printer, Scanner and CPU etc.


Networking is a process in which 2 or more computer systems interconnect with each other in order to share resources or data/information.


There are many types of computer networks-

  1. LAN
  2. MAN
  3. WAN
  4. PAN etc.

1 ) LAN –

  • LAN stands for Local Area Network.
  • This network usually use to connect systems and devices in a small area such as building, hospital, school, Office buildings and home etc.
  • Inexpensive or Low cost
  • Required less number of devices
  • High speed
  • Ethernet or WIFI are two ways to enable LAN
  • LAN can be established using cable or wireless

2) MAN-

  • MAN stand for Metropolitan area network.
  • This network is larger than LAN and smaller than WAN.
  • Required more number of devices
  • Provide High speed
  • It is used to connect multiple nodes of a city.
  • It can be operated and owned by government or any cooperation.
  • More expensive than LAN but Less expensive than WAN

3) WAN-

  • WAN stands for Wide Area Network
  • It provides networking between cities and countries.
  • This network can established using cable or wireless.
  • More expensive.
  • WAN establishes using satellite, infrared or microwave transmission.

4) PAN-

Devices used for Networking-


  • Router is a networking device. This device receives data packets from one system and transferred data to concerned system.
  • It maintains routing table. This table has route of all nodes.
  • It choose best route or path to transmit data to the concerned device.
  • Router connects the network.
  • It works on Network Layer.


  • Switches is a networking device used to connect different devices within a network.
  • Switch transfer the data to the concerned devices only.
  • It receives, process and deliver the data packet to the concerned device.
  • It works on Data link layer.
  • Switch creates the network


    • Hub is a networking device used to connect different networking devices or segments physically together.
    • It works on physical layer
    • It receive data from one and send data to the all ports.
    • Hubs normally used in those network that use twisted pair cabling for connecting the device.
    • There are two types of Hubs-
  • Active Hubs- Active hubs are smarter than passive hub. They transfer the signals after regenerating, concentrate and strengthen to their destination. Active hubs are also termed as Repeater.
  • Passive Hubs- Passive hubs are just conduit(Channel) for the data to transmit data from one device to another device.


  • It is a networking device used to connect one LAN to another LAN that uses the same protocol.
  • It works on data link layer.


  • It is a networking device that is used to receive data from one device, regenerates the signal and transfer the regenerated to intended device.
  • It works on physical layer.
  • Repeaters overcomes the problem of attenuation caused due to electromagnetic interference and high distance between communicating device. Signal loss problem during transmission can be overcome by using the series of repeaters.
  • Repeaters can be used in wireless communication or in wired communication.



  • Gateway device is used to connect different LANs when there are different technologies implemented by these different LANs which are to be connected together..
  • This device works at transport layer and above.


  • Modem Stands Modulator and Demodulator.
  • Modulation means conversion of digital data to analog data and demodulation means conversion of analog data to digital data.
  • Modem works at physical Layer.


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