Basic CS-Networks [TCS Placement]: Sample Questions 43 - 45 of 133

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Question 43

Networks
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Describe in Detail

Essay▾

What is Error Detection? What are its methods?

Explanation

  • Data can be corrupted during transmission and hence errors must be detacted and corrected.
  • Error detection uses redundancy- by adding extra bits for detecting errors.
  • Error detection refers to the techniques used to detect noise or other impairments introduced into data while it is transmitted from source to destination.
  • Common error detection methods are
    1. Vertical Redundancy Check (VRC)
    2. Longitudinal Redundancy Check (LRC)
    3. Cyclic Redundancy Check (CRC)
    4. Checksum

Question 44

Networks
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Write in Short

Short Answer▾

What is RAID?

Explanation

  • It is a method for providing fault tolerance by using multiple hard disk drives. Short for redundant array of independent disks.
  • Was defined as redundant array of inexpensive disks, but now refers to redundant array of inexpensive disks.
  • RAID uses multiple disks to provide fault tolerance, improve performance, or to increase capacity.
  • RAID is used frequently on servers but not necessary for personal computers.

Question 45

Networks
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Describe in Detail

Essay▾

What is OSPF?

Explanation

  • Open Shortest Path First (OSPF) is a link state routing protocol (LSRP) using the Shortest Path First (SPF) or Dijkstra՚s algorithm to calculate shortest connection path between known devices.
  • It is an Interior Gateway Protocol (IGP) routing Internet Protocol (IP) packets.
  • OSPF has following advantages:
    • Scales well
    • Can route traffic along multiple paths
    • Uses Internet՚s topology to make accurate routing decisions
  • For example, to go from city A to city M there are two options:
  • Travel via cities B and C. The route would be ABCM. And the distance (or bandwidth cost) for A-B is miles, B-C is miles and C-M is 10 miles.
  • Travel via city F. The route would be AFM. And the distance for miles and F-M is miles.
  • Shortest route has least amount of total distance.
  • Thus, ABCM is the better option even though two cities have to be traversed. Second option with a single city has cost of .
  • OSPF does similar calculation for shortest path between the source and destination based on link bandwidth cost.
Given the Image is Define the OSPF (Open Shortest Path First)

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