Virtual Labs

Physical Clocks and Clock Synchronization

What is the primary challenge in synchronizing physical clocks in distributed systems?

a: Clocks run too fast Explanation

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b: Clocks run too slow Explanation

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c: Clocks drift at different rates Explanation

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d: Clocks are inaccessible Explanation

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What is a 'time server' in clock synchronization?

a: A server hosting web pages Explanation

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b: A server providing reference time Explanation

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c: A server storing files Explanation

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d: A server running databases Explanation

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What is the core principle of Cristian's algorithm?

a: Slow down all clocks uniformly Explanation

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b: Speed up all clocks uniformly Explanation

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c: Adjust client clock using server time and network delay Explanation

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d: Stop all clocks temporarily Explanation

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How does NTP handle variable network delays?

a: Ignores delay variation Explanation

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b: Assumes constant delay Explanation

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c: Uses statistical filtering of measurements Explanation

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d: Requires manual delay input Explanation

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What is the purpose of NTP's hierarchical server structure?

a: To increase system complexity Explanation

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b: To distribute load and improve accuracy Explanation

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c: To reduce system reliability Explanation

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d: To increase operational costs Explanation

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Beyond the server timestamp, what must a client consider before setting its clock?

a: Server's geographic location Explanation

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b: Network round-trip time Explanation

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c: Server's uptime duration Explanation

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d: Number of connected users Explanation

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Why is directly setting a clock backward problematic when it's ahead of server time?

a: Events can appear to occur in the past Explanation

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b: It damages clock hardware Explanation

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c: It crashes the server Explanation

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d: It violates physics laws Explanation

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How can systems handle clocks that are ahead without jumping backward?

a: Always set clocks forward only Explanation

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b: Gradually slow the clock until synchronized Explanation

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c: Ignore the server's time Explanation

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d: Shut down the system Explanation

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What is the trade-off between synchronization frequency and network traffic?

a: Higher frequency reduces traffic Explanation

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b: Higher frequency increases traffic Explanation

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c: No trade-off exists Explanation

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d: Trade-off depends on time of day Explanation

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In a scenario where network asymmetry exists (different forward and return path delays), which synchronization method is most affected?

a: NTP with multiple servers Explanation

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b: Cristian's algorithm Explanation

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c: GPS-based synchronization Explanation

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d: Atomic clock synchronization Explanation

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A financial trading system requires timestamps accurate to within 1 millisecond. Which approach is most suitable?

a: Cristian's algorithm over the internet Explanation

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b: Manual clock setting daily Explanation

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c: NTP with stratum 1 servers or PTP Explanation

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d: System clock without synchronization Explanation

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What happens if a client's clock drift rate is 50 ppm and it synchronizes once per day?

a: Clock stays perfectly synchronized Explanation

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b: Clock drifts approximately 4.3 seconds per day Explanation

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c: Clock stops working Explanation

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d: Clock drift is negligible Explanation

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In a distributed database system, why might logical clocks be preferred over physical clock synchronization?

a: Logical clocks are always more accurate Explanation

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b: Logical clocks capture causality without requiring time synchronization Explanation

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c: Logical clocks are easier to implement Explanation

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d: Physical clocks cannot be synchronized Explanation

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