Fundamental to fault tolerance is the recovery from an error, replacing an erron

Question

Fundamental to fault tolerance is the recovery from an error, replacing an erroneous state with an error-free state.
    a. true
    b. false

Using timers and resending messages or replies cannot harm a distributed system.
    a. true
    b. false

A key feature of scalable reliable multicasting (SRM) is that successful delivery is never acknowledged by the receiver. Only negative acknowledgements are returned as feedback.
    a. true
    b. false

The cause of an error is called a fault.
    a. true
    b. false

A highly reliable system may show a high degree of availability, especially if failures can be detected and repaired automatically.
    a. true
    b. false

Explanation / Answer

1. True - Fault tolernace is all about detecting the erreor, process the error, error recovery , resume the normal operation
2. True : Timers and resending are normal phenomenon in ditriubuted system where a possible case will be that sender waits for certain acknowledgement for certain amount of time and if it does not receive that it will resend the message or information.It will not harm the system but too much of such failures can affect the performance of the system.
3.True: in SRM, receivers never acknowledge the successful delivery of a multicast message, but instead, report only when they are missing a message.Only negative acknowledgments are returned as feedback
4.True : Fault causes the error in the system.Error is the difference between the actual output and expected output.
5.True: if faults are detected and repaired automatically, the system will not go down and its availability will definatly be increased.

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