Computer Network
Unit 1
Q 1. What are the topologies in computer n/w ?
Ans: Network topologies are categorized into the following basic types:
Bus Topology
Bus networks use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector.
Ring Topology
In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction. A failure in any cable or device breaks the loop and can take down the entire network.
Star Topology
Many home networks use the star topology. A star network features a central connection point called a "hub" that may be a hub, switch orrouter.
Tree Topology
Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices.
Mesh Topology
Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination.
Q 2. What is Computer n/w ?
Ans: A computer network is a group of two or more computers connected to each electronically. This means that the computers can "talk" to each other and that every computer in the network can send information to the others.
Q 3. How we arrived 7 layers of OSI reference model? Why not less than 7 or more than 7 ?
Ans: The ISO looked to create a simple model for networking. They took the approach of defining layers that rest in a stack formation, one layer upon the other. Each layer would have a specific function, and deal with a specific task. Much time was spent in creating their model called "The ISO OSI Seven Layer Model for Networking". In this model, they have 7 layers, and each layer has a special and specific function.
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