Virtual Labs

In a scalar logical clock system, what is the initial clock value for all processes?

a: 1 Explanation

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b: 0 Explanation

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c: Current physical time Explanation

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d: Process ID Explanation

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What is the purpose of the happens-before relation in distributed systems?

a: To measure physical time differences Explanation

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b: To establish causal ordering between events Explanation

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c: To synchronize clocks across processes Explanation

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d: To determine network latency Explanation

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What does the 'd' represent in the scalar logical clock increment rule C_i ← C_i + d?

a: The process ID Explanation

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b: The increment amount (usually 1) Explanation

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c: The number of messages sent Explanation

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d: The physical time difference Explanation

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What happens to logical clock values when a message is sent between processes?

a: Only the sender's clock is incremented Explanation

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b: Only the receiver's clock is incremented Explanation

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c: Both sender and receiver clocks are incremented according to specific rules Explanation

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d: Neither clock changes Explanation

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If process P1 has clock value 5 and receives a message with timestamp 8, what will P1's clock value be after processing the message (assuming increment d=1)?

a: 6 Explanation

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b: 8 Explanation

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c: 9 Explanation

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d: 13 Explanation

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In practice, how is total ordering typically achieved with scalar logical clocks?

a: By using the process with the highest clock value Explanation

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b: By using tie-breaking mechanisms like process IDs when timestamps are equal Explanation

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c: By synchronizing all clocks to the same value Explanation

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d: By using vector clocks instead Explanation

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What is a fundamental limitation of scalar logical clocks compared to vector clocks?

a: They cannot detect concurrency definitively Explanation

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b: They use more memory Explanation

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c: They are slower to compute Explanation

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d: They require physical clock synchronization Explanation

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In the context of distributed systems, what does monotonicity mean for scalar logical clocks?

a: Clock values always increase and never decrease within a process Explanation

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b: All processes have identical clock values Explanation

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c: Clock values represent physical time accurately Explanation

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d: Messages are delivered in timestamp order Explanation

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How do scalar logical clocks ensure that the happens-before relation is preserved in a distributed system with message losses?

a: They retransmit lost messages automatically Explanation

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b: They assume reliable message delivery for correctness Explanation

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c: They use acknowledgments to confirm message receipt Explanation

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d: They maintain backup timestamps Explanation

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Scalar Logical time