Exams Big Questions

Question 1

What is the most significant difference between a synchronous and asynchronous distributed sytem

Answer 1

possibility of perfect failure detectors

Question 2

When is the TCP window size a limiting factor for high capacity communication?

Answer 2

over long fat communication limks

Question 3

Can two Unix processes simultaneous write to different positions in a single file?

Answer 3

Yes, the two processes will of course have independent file table entries that will have different positions in the file.

Question 4

Show by example how a dead lock situation is falsely detected if one only consider information gathered from the nodes in a system. How does the snapshot algorithm prevent this?

Answer 4

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Question 5

In an active replication implementation of a fault tolerant server the group service will multicast messages in total order. Why is this important? How could we relax the rules, is total order always required for all requests?

Answer 5

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Question 6

When implementing a logging service you have the alternative to use vector clocks or Lamport clocks. What are the pros and cons of choosing vector clocks? Describe two scenarios, one for each.

Answer 6

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