Basic CS-Networks [3i Infotech Placement]: Sample Questions 57 - 59 of 90

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Question 57

Networks
Edit

Describe in Detail

Essay▾

Name of 7 layers of the OSI stack.

Explanation

Define OSI Model in Image
  • Application layer
  • Presentation layer
  • Session layer
  • Transport layer
  • Network Layer
  • Data link layer
  • Physical layer

Question 58

Networks
Edit

Write in Short

Short Answer▾

Why should you care about the OSI reference model?

Explanation

  • OSI provides a framework for understanding network operations and design- designing new protocols, stacks and entire networks.
  • Not all network stacks obey the OSI fully, all the time with distinct layers but it still provides a useful system, which can be understood and obeyed throughout the world.
  • ISO standard for Networks defines this networking framework for implementing protocols in seven layers.
  • Convention and rules for network are collectively known as layer protocol.
  • OSI is considered a primary standard for internetworking and inter computing.

Question 59

Networks
Edit

Describe in Detail

Essay▾

What are important topologies for networks?

Explanation

Network Topology in Image

Bus Topology

BUS Topology in Image
  • A common backbone to connect all devices.
  • Also called a line topology.
  • Provides shared single cable communication medium for all devices connected using interface connector.

Advantages:

  • Relatively easy to install and requires less cabling.
  • Works best with a limited number of devices.
  • Bus topology costs very less.

Disadvantages:

  • Difficult to detect and troubleshoot fault at individual station.
  • Not suitable for networks with heavy traffic.
  • Might require exclusive access to the bus for sending data.

Star Topology

Star Topology in Image
  • One of the most common network setups.
  • Each node connects to a central network device like a hub, switch, or computer.
  • Star topology is also known as a star network.

Advantages:

  • Easy to add another computer.
  • If one computer on the network fails, the rest of the network continues to function normally.

Disadvantages:

  • Not scalable- the central network device determines the performance and number of nodes the network can handle.
  • Single point of failure- if the central computer, hub, or switch fails, the entire network goes down and all computers are disconnected from the network.

Ring Topology

Ring Topology in Image
  • Configuration with devices connected to each other in a circular shape.
  • Also called active topology- messages are passed to each device in the ring.
  • Highly efficient and handles heavier loads better than bus topology.

Advantages:

  • All data flows in one direction, reducing the chance of packet collisions.
  • A network server is not needed to control network connectivity between each workstation.
  • Data can transfer between workstations at high speeds.

Disadvantages:

  • The entire network will be impacted if one workstation shuts down.
  • The hardware needed to connect each workstation more expensive than Ethernet cards and hubs.

Tree Topology

Tree Topology in Image
  • Special structure with connected elements arranged like the branches of a tree.
  • A tree network is a bus network of star networks- number of star networks connected using bus.
  • Also called Expanded Star Topology.

Advantages:

  • Expansion is easy.
  • Error detection and correction is easy.
  • If one segment is damaged, other segments are not affected.
  • Each segment is provided with dedicated point-to-point wiring to the central hub

Disadvantages:

  • Maintenance of many nodes and segments becomes difficult.
  • Scalability of the network depends on the type of cable used.

Mesh Topology

Mesh Topology in Image
  • Each of the network node, computer and other devices, are interconnected with one another.
  • A true mesh topology is the one where every node is connected to every other node in the network- provides fastest possible way to reach a computer from any other computer.
  • Commonly used in wireless networks.
  • Flooding or routing technique is used in mesh topology.

Advantages:

  • Data can be transmitted simultaneously from devices.
  • Even if one of the components fails there is always an alternative
  • Expansion and modification in topology can be done without disrupting other nodes

Disadvantages:

  • Chances of redundancy in many of the network connections.
  • Cost of this network is way too high compared to other network topologies.

Hybrid Topology

Hybrid Topology in Image
  • Network topology is a connection of various links and nodes, communicating with each other for transfer of data.
  • There is no strict arrangement of nodes and devices.
  • For example, a ring topology in one department connected with tree topology in another department using a bus- hybrid topology.

Advantages:

  • Reliable
  • Scalable
  • Flexible
  • Effective

Disadvantages:

  • Complexity of design
  • Costly hub
  • Costly infrastructure

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