Cloud Computing and Distributed Systems - - Unit 7 - Week 5 PDF

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NPTEL (https://swayam.gov.in/explorer?ncCode=NPTEL) » Cloud Computing and Distributed Systems (course)

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Assignment-5 The due date for submitting this assignment has passed.

How does an NPTEL online course work? Week 0 Assignment 0

Due on 2021-02-24, 23:59 IST.

Assignment submitted on 2021-02-22, 21:19 IST 1) Consider the following statements:

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Statement 1: In the synchronous system model, consensus is impossible to solve. Week 1 Statement 2: In the asynchronous system model, consensus is solvable. Week 2 Statement 3: Paxos provides safety and eventual liveness. Week 3 Only statement 1 is true Week 4

Only statement 1 and statement 2 are true Only statement 2 and statement 3 are true

Week 5 Consensus in Cloud Computing and Paxos (unit? unit=45&lesson=46)

Only statement 3 is true Yes, the answer is correct. Score: 1 Accepted Answers: Only statement 3 is true 2) Find out the correct model for the given assumptions of a system:

Byzantine Agreement (unit? unit=45&lesson=47)

Assumption 1: Each message is received within bounded time.

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Failures & Recovery Approaches in Distributed Systems (unit? unit=45&lesson=48) Week 5: Lecture Material (unit? unit=45&lesson=49) Quiz : Assignment-5 (assessment? name=83) Feedback for Week 5 (unit? unit=45&lesson=94)

Assumption 2: Drift of each process’ local clock has a known bound. Assumption 3: Each step in a process takes lb < time < ub , where lb represents lower bound and ub represents an upper bound. Asynchronous distributed system Synchronous distributed system On demand computing system Parallel processing system Yes, the answer is correct. Score: 1 Accepted Answers: Synchronous distributed system 3) Consider the given table of agreement problems and match the correct pair:

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Assignment-5 Solution (unit? unit=45&lesson=97)

Week 6 Week 7 (P): (i), (Q): (ii), (R): (iii) Week 8

(P): (iii), (Q): (ii), (R): (i) (P): (iii), (Q): (i), (R): (ii)

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(P): (ii), (Q): (iii), (R): (i) Yes, the answer is correct. Score: 1 Accepted Answers: (P): (iii), (Q): (i), (R): (ii)

LIVE Session 4) True or False ?

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Consider the following statement: “Pease showed that in a fully connected network, it is possible to reach an agreement if number of faulty processors ‘f’ exceeds (n-1)/3 where n = number of processors”. True False Yes, the answer is correct. Score: 1 Accepted Answers: False 5) True or False ? Consider the following statement:

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“Byzantine agreement cannot be reached among three processors if one processor is faulty” True False Yes, the answer is correct. Score: 1 Accepted Answers: True 6) Consider the following statement:

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True or False ? “Koo-Toueg algorithm is a uncoordinated checkpointing and recovery technique that takes a consistent set of checkpointing and avoids domino effect and livelock problems during the recovery” True False Yes, the answer is correct. Score: 1 Accepted Answers: False 7) Messages whose ‘send’ is done but ‘receive’ is undone due to rollback are called_________________.

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In-transit message Lost messages Orphan messages Duplicate messages Yes, the answer is correct. Score: 1 Accepted Answers: Lost messages 8) Cascaded rollback which causes the system to roll back to too far in the computation 1 point (even to the beginning), in spite of all the checkpoints is known as_______________________. Rollback Phantom Effect Domino Effect Livelock Yes, the answer is correct. Score: 1 Accepted Answers: Domino Effect 9) Messages with ‘receive’ recorded but message ‘send’ not recorded and do not arise if 1 point processes roll back to a consistent global state are called______________________

In-transit messages Lost messages Orphan messages Duplicate messages Yes, the answer is correct. Score: 1 Accepted Answers: Orphan messages 10) The ____________________may arise when a process rolls back to its checkpoint after a failure and requests all the other affected processes also to roll back. Rollback Phantom Effect Domino Effect Livelock problem Yes, the answer is correct. Score: 1 Accepted Answers: Livelock problem

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