Basic_continued_CN.md

Q.1 Difference between Unicast, Broadcast and Multicast in Computer Network

i) Unicast

- This type of information transfer is usefull in One-to-One transmission,
  i.e When there is a participation of single sender and a single reciever.

ii) Brodcast

• Limited Broadcasting:

  - when we have to send stream of packets to all the devices in the same network then this type 
    of casting is used.
  - We achieve limited broadcasting by appending the Limited broadcast address 
    (i.e by making all the 32 bits of IP address set to 1 ==> 255.255.255.255) in the destination address 
    of a packet header which is reserved for information transfer to all the recipients from 
    a single sender over the network. 
  

• Direct Broadcasting:

   - This is useful when a device in one network wants to transfer packet stream to all the devices 
     over the other network. 
   - This is achieved by translating all the Host ID part bits of the destination address to 1, 
     referred as Direct Broadcast Address in the datagram header for information transfer.
   - This mode is mainly utilized by television networks for video and audio distribution. 
   - One important protocol of this class in Computer Networks is Address Resolution Pr
  

iv) Multicasting

    -  In multicasting, one/more senders and one/more recipients participate in data transfer traffic.

Q.2 Different types of Physical Topologies are

=> Point to Point

• Point-to-point topology is the easiest of all the network topologies. In this method, the network consists of a direct link between two computers.

Advantages:

• This is faster and highly reliable than other types of connections since there is a direct connection.
• No need for a network operating system.
• Does not need an expensive server as individual workstations are used to access the files
• No need for any dedicated network technicians because each user sets their permissions.

Disadvantages:

• The biggest drawback is that it only be used for small areas where computers are in close proximity.
• You can't back up files and folders centrally
• There is no security besides the permissions. Users often do not require to log onto their workstations.

=> Bus Topology

• Bus topology uses a single cable which connects all the included nodes.
• The main cable acts as a spine for the entire network. One of the computers in the network acts as the computer server.
• When it has two endpoints, it is known as a linear bus topology.

Advantages:

• Cost of the cable is very less as compared to other topology, so it is widely used to build small networks.
• Famous for LAN network because they are inexpensive and easy to install.
• It is widely used when a network installation is small, simple, or temporary.
• It is one of the passive topologies. So computers on the bus only listen for data being sent, that are not responsible for moving the data from one computer to others.

Disadvantages:

• In case if the common cable fails, then the entire system will crash down.
• When network traffic is heavy, it develops collisions in the network.
• Whenever network traffic is heavy, or nodes are too many, the performance time of the network significantly decreases. Cables are always of a limited length.

=> Ring Topology

• In a ring network, every device has exactly two neighboring devices for communication purpose.
• It is called a ring topology as its formation is like a ring. In this topology, every computer is connected to another computer.
• Here, the last node is combined with a first one.
• This topology uses token to pass the information from one computer to another.
• In this topology, all the messages travel through a ring in the same direction.

Advantages:

• Easy to install and reconfigure.
• Adding or deleting a device in-ring topology needs you to move only two connections.
• The troubleshooting process is difficult in a ring topology.
• Failure of one computer can disturb the whole network.
• Offers equal access to all the computers of the networks
• Faster error checking and acknowledgment.

Disadvantages:

• Unidirectional traffic.
• Break in a single ring can risk the breaking of the entire network
• Modern days high-speed LANs made this topology less popular.
• In the ring, topology signals are circulating at all times, which develops unwanted power consumption.
• It is very difficult to troubleshoot the ring network.
• Adding or removing the computers can disturb the network activity.

=> Star Topology

• In the star topology, all the computers connect with the help of a hub.
• This cable is called a central node, and all other nodes are connected using this central node. It is most popular on LAN networks as they are inexpensive
  and easy to install.

Advantages:

• Easy to troubleshoot, set up, and modify.
• Only those nodes are affected, that has failed. Other nodes still work.
• Fast performance with few nodes and very low network traffic.
• In Star topology, addition, deletion, and moving of the devices are easy.

Disadvantages:

• If the hub or concentrator fails, attached nodes are disabled.
• Cost of installation of star topology is costly.
• Heavy network traffic can sometimes slow the bus considerably.
• Performance depends on the hub's capacity
• A damaged cable or lack of proper termination may bring the network down.

=> Mesh Topology

• The mesh topology has a unique network design in which each computer on the network connects to every other.
• It is develops a P2P (point-to-point) connection between all the devices of the network.
• It offers a high level of redundancy, so even if one network cable fails, still data has an alternative path to reach its destination.

Advantages:

• The network can be expanded without disrupting current users.
• Need extra capable compared with other LAN topologies.
• Complicated implementation.
• No traffic problem as nodes has dedicated links.
• It has multiple links, so if any single route is blocked, then other routes should be used for data communication.
• P2P links make the fault identification isolation process easy.
• It helps you to avoid the chances of network failure by connecting all the systems to a central node.

Disadvantages:

• Installation is complex because every node is connected to every node.
• Dedicated links help you to eliminate the traffic problem.
• A mesh topology is robust.
• Every system has its privacy and security
• It is expensive due to the use of more cables. No proper utilization of systems.
• It requires more space for dedicated links.
• Because of the amount of cabling and the number of input-outputs, it is expensive to implement.
• It requires a large space to run the cables.

=> Tree Topology

• Tree topologies have a root node, and all other nodes are connected which form a hierarchy.
• So it is also known as hierarchical topology. This topology integrates various star topologies together in a single bus, so it is known as a Star Bus
  topology.
• Tree topology is a very common network which is similar to a bus and star topology.

Advantages:

• Failure of one node never affects the rest of the network.
• Node expansion is fast and easy.
• Detection of error is an easy process
• It is easy to manage and maintain

Disadvantages:

• It is heavily cabled topology
• If more nodes are added, then its maintenance is difficult
• If the hub or concentrator fails, attached nodes are also disabled.

=> Hybrid Topology

• Hybrid topology combines two or more topologies. You can see in the above architecture in such a manner that the resulting network does not exhibit one of
  the standard topologies.
• For example, as you can see in the above image that in an office in one department, Star and P2P topology is used. A hybrid topology is always produced when two different basic network topologies are connected.

Advantages

• Offers the easiest method for error detecting and troubleshooting
• Highly effective and flexible networking topology
• It is scalable so you can increase your network size

Disadvantages

• The design of hybrid topology is complex
• It is one of the costliest processes

Q.3 LAN vs MAN vs WAN