Introduction to Computer Networks - CS XII (CBSE)

The Computer Networking

Definition:

Computer Network is a collection of two or more computers and other devices linked together to share resources.

Different mediums can be used to connect these devices together:

  • Copper wire,
  • optical fibre,
  • microwave, or
  • satellites

Each connected computer or device connected to a network is called  a node. Apart from computers other devices that can be connected to a network are:

  • Printer,
  • Modem, or
  • any other device capable of sending or receiving data.

Computer Networks – Important information the form of Questions and answers –

Here you will find Computer networks class 12 notes for 2024-25 which will cover topics such as network types, network communication, transmission media, network protocols,  Network topologies, Network types, Network devices and related as per syllabus in the form of question and answers and explanations to understand better.

1. What is Computer Network?

A collection of computers that are connected electronically to share data, resources (hardware and software), and software programs. It also act as a best Communication medium in today’s modern world.

2. Define the term Node?

Node is the term used for Computer or any other device for example printers, laptops, scanners, mobile devices etc. attached or connected to a Computer Network system.

3. What are the advantages of Computer Networks?

There are so many advantages of Computer Networks. Few of the important benefits are:

  1. Resource Sharing
  2. Cost Efficient
  3. Increased Storage Space (because of sharing)
  4. Multi-user Environment
  5. Improved or fast communication
  6. Instant information availability
  7. Network Resources available 24/7 – 365 days

4. What are the different Types of Computer Networks?

The different types of computer Networks are:

  1. Personal Area Network (PAN)
  2. Local Area Network (LAN)
  3. Metropolitan Network (MAN) 
  4. Wide Area Network (WAN)

5. What is Personal Area Network?

A personal area network (PAN) is a very small network that interconnects devices within a small area of just a few meters.

  1. The main purpose is enable devices in a Small Office or Home Office environment.
  2. This can be done to communicate and share resources.
  3. This can be done by connecting wirelessly or using wires

6. What are the main properties of Private Area Network (PAN)?

The main properties of PAN are:

  1. Mostly it used with  wire-less technology (Wi-Fi)
  2. It covers small distance of 10 to 30 meters
  3. It is a kind of private network, because mostly it is owned by an individual.

7. What is Local Area Network?

LAN or local area network is a collection of computers and devices connected together within a single physical location, For example:  building (school for example), office, or home.

  1. LAN is larger than PAN. It can have large number of devices attached together and a large number of user accessing this network.
  2. All the devices attached are in close proximity

8. What are the properties of a Local Area Network (LAN) ?

The main properties of LAN are:

  1. LAN covers small geographical area which is not more than 1 to 5 kilometers.
  2. This network is usually a private network owned by a single person or a company.
  3. Easy Installation and maintenance of network
  4. It is a fast Network as compared to other types of networks.

9. What is a Metropolitan l Area Network (MAN) ?

10. What are the properties of a Metropolitan Area Network (LAN) ?

The main properties of MAN are:

  1. MAN can span across 5 to 50 kilometers.
  2. Usually owned and operated by organizations or associations providing services.
  3. It is usually a public network.
  4. It is also a high speed network.

11. What is Wide Area Network (WAN) ?

WAN also known as Wide Area Network is a large computer Network that can span across large geographical area.

  • It is a computer network that can be comprised of two or more LANs or MANs.
  • It is large enough that it can span across multiple cities, states and countries.

12. What are the properties of Wide Area Network (WAN) ?

  1. It is more often a Public Network.
  2. As the name suggests it can span across long distance.
  3. It is usually owned by large National as well as multi-national organizations for examples National level Banks, Railways etc.
  4. Because of its size – it is usually not as fast as LAN or MAN.

Networking Topologies

Definition:

Any computer Network is made possible through:

  1. Physical (cables and other mediums) and
  2. Logical (network operating system) connections.

Network topology is thus the different ways computers and other devices or nodes can be connected or arranged together physically  and logically.

The arrangement of nodes and connections in a network decides how devices can communicate with each other.

Network topologies – Important information the form of Questions and answers –

There are so many Different Network Topologies available for example Star, ring, Bus, Tree, Mesh etc. Each one has its own benefits and work efficiently in certain scenarios.

13. What do you mean by Network Topologies ?

Network topology can be seen as schematic description of the arrangement of the physical and logical elements of a Computer network. There are different types of network topologies:

  1. Star Topology
  2. Ring Topology
  3. Bus Topology
  4. Tree Topology
  5. Mesh Topology

14. What do you mean by Star Topology?

Start topology is one of the most popular topology. In this topology:

  1. Computers or nodes are not connected to one another, They are connected to the central HUB (or switch).
  2. For communication, the message sent by the node is received by the central HUB or Switch which sends the information to target node.

Networking -Star Topology

Networking -Star Topology

15. What are the advantages and disadvantages of Star Topology?

Advantages of Star Topology are:

  • Easy to install and update network
  • It is one of the less expensive topology.
  • If anything goes wrong, it is easy to detect the problem and solve the issue.
  • If you want to add a new node, its very easy to implement.

There are few disadvantages as well, these are:

  • Entire network depends upon the central HUB – for its speed and efficiency.
  • Entire network goes down If anything goes wrong with the central HUB.
  • Requires more cable because every node is connected separately to the HUB.

 

16. What do you mean by ring Topology?

Ring Topology connects all the nodes in a circular fashion. Where each node is connected to its two neighboring nodes.

  • Data transmitted using this topology travels from one node to another until it reached the destination node.

Networking - Ring Topology

Networking – Ring topology

17. What are the Advantages and dis-advantages of Ring Topology?

Ring topology has its own advantages and disadvantages.

Advantages:

  • It is a high speed communication network.
  • Each node has same access to all the network resources.
  • It is easy to maintain and  troubleshoot networking issues.
  • Data transmission does not require server.
  • Data travels unidirectionally. 

Disadvantages:

  • It is comparatively less secured network system.
  • Failure of one node will result in entire network down.
  • It is Comparatively more expensive.
  • It is also slower as compared to star topology.

18. What do you mean by Bus Topology?

Bus Topology is yet another very popular and also simplest Network Topology. All the nodes in a Bus Topology are connected through a single cable also called backbone.

  • Information transmitted by any node reaches out to every node on the network, but
  • Since information transferred is in the form of packets and each packet has an address telling this information is meant for which node – Only that node can access and process that information for which that information was sent to.

Networking - Bus topology

Networking – Bus topology

19. What are the advantages and disadvantages of Bus Topology?

Bus Topology also has its own advantages and disadvantages.

Advantages:

  • Requires less caballing as compared to other networks, because it requires only single cable connecting all the nodes.
  • Less Expensive.
  • Easy to design and install.
  • You can also easily expand the network as per future requirements.
  • Best suitable for small sized networks.

Disadvantages:

  • Its easy to install but difficult to find the fault, if something goes wrong.
  • If something goes wrong with backbone cable, entire network goes down.
  • Not suitable for large networks.
  • It is a slow network as compared to others. 

 

20. What is Tree Topology?

 

Tree type of topology creates a parent-child relationship between two nodes. It is a Hierarchical relationship between nodes.

  • Creates a parent child hierarchy, because of which it is known as Tree Topology.
  • There can be only one connection between two nodes, and between two nodes there can be only one mutual connection.
  • It is also know and Star-Bus topology it is internally a kind of  combination of both star and Bus topology.

Networking - Tree Topology

Networking – Tree Topology

21. What are the Advantages and Disadvantages of tree Topology?

 

Tree topology has its own advantages and disadvantages.

Advantages:

  • Most suitable for the networks of large size.
  • New nodes can be added easily without interrupting the entire network.
  • If any node stops working (fails) it does not affects the entire network.
  • It is also well secured Network System.

Disadvantages:

  • It is more complex Network System.
  • It is more Expensive Network System.
  • Since it is a combination of BUS and Star topology it depends upon one central cable (also known as backbone cable). If that fails entire network gets affected.
  • Since it is a hierarchical structure – if higher level node fails it affects the performance of node which is at the next level (or child node).
  • Because of its complex structure its maintenance is also not easy. 

22. What is Mesh Topology?

 

Mesh topology is yet another type of topology where each node is connected to every other node on the network individually. Because of which:

  • Each node is capable of sending and receiving information to/from any other node on the network.
  • Connection between these nodes can both wired or wireless.
  • It does not implements network with the help of any central Server or Switch/Hub.

Networking - Mesh Topology

Networking – Mesh Topology

23. What are the Advantages and Disadvantages of Mesh Topology?

Mesh Topology also has its own advantages and disadvantages.

Advantages:

  • It is capable of managing large amount of traffic easily, because of its structure.
  • It is a highly secured Network
  • The connections between each node can be both wired or wireless.
  • It is a robust network:
    • New node can be added easily without interrupting the entire network.
    • Failure of one node does not puts down the entire network.

Disadvantages:

  • Connecting each node to every other node makes it a complex network.
    • Because of this it is difficult to install and maintain.
    • Mode expensive as compared to other networks.
    • Consumes more power as each node has to remain active all the time because it is also behaving like a router.

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