NPTEL Cloud Computing and Distributed Systems Week 4 Assignment Answers 2025

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NPTEL Cloud Computing and Distributed Systems Week 4 Assignment Answers 2025

1. Assign Lamport timestamps to the events (a, b, c, d, e, f) as shown in the figure:

  • a: 6, b: 2, c: 6, d: 7, e: 7, f: 8
  • a: 1, b: 2, c: 2, d: 3, e: 4, f: 2
  • a: 6, b: 7, c: 6, d: 7, e: 7, f: 8
  • a: 6, b: 7, c: 6, d: 7, e: 8, f: 9
Answer :- For Answers Click Here

2. Which event is concurrent with the vector clock (2, 7, 3) ?

  • (4, 9, 4)
  • (1, 7, 4)
  • (1, 5, 1)
  • (5, 7, 3)
Answer :-

3. A client gets a timestamp of 3:12:30.500 from a time server. The elapsed time between the request and response was 20 msec (0.020 sec). The current time on the client is 3:12:30.510. Using Cristian’s algorithm i.e. server time + ½(elapsed time), what is the time set on the client ?

  • 3:12:30.480
  • 3:12:30.490
  • 3:12:30.510
  • 3:12:30.520
Answer :-

4. A client’s clock reads 3:20:00. The server’s clock reads 3:10:00 when they synchronize using the Berkeley algorithm. Assume message delays are negligible. What is the time at the client after synchronization ?

  • 3:20:00
  • 3:10:00
  • 6:30:00
  • 3:15:00
Answer :-

5. True or False ?

DTP (Datacenter Time Protocol) uses the physical layer of network devices to implement a decentralized clock synchronization protocol.

  • True
  • False
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6. The properties hold for quorums in a coterie are:

  • Total ordered set property
  • Intersection property
  • Minimality property
  • Both Intersection and Minimality property
Answer :-

7. True or False ?

The Chandy-Lamport global snapshot algorithm works correctly for non-FIFO channels.

  • True
  • False
Answer :-

8. Find out the correct property to solve mutual exclusion in distributed system:

Property 1: At most one process executes in critical section at any time

Property 2: Every request for a critical section is granted eventually

Property 3: Requests are granted in the order they were made

  • Property 1: Liveness, Property 2: Fairness, Property 3: Safety
  • Property 1: Safety, Property 2: Fairness, Property 3: Liveness
  • Property 1: Fairness, Property 2: Safety, Property 3: Liveness
  • Property 1: Safety, Property 2: Liveness, Property 3: Fairness
Answer :-

9. Consider the following statements:

Statement 1: Lamport’s algorithm achieves mutual exclusion.

Statement 2: Lamport’s algorithm is fair.

  • Only statement 1 is true
  • Only statement 2 is true
  • Both statements are true
  • Both statements are false
Answer :-

10. ___________________provides Advisory locks only and doesn’t guarantee mutual exclusion unless every client checks lock before accessing resource.

  • Paxos
  • Google’s Chubby
  • Cassandra
  • Microsoft Azure
Answer :- For Answers Click Here

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