Given the following cron expression "0 1 * America/Los_Angeles", how will the task behave when changing from Daylight Savings Time to Standard Time, moving the clock one hour back?

Question

Options

• AThe task will run once.
• BThe task will run twice.
• CThe task will not run.
• DThe task will fail with an error.

• A
  4% (1)
• B
  70% (16)
• C
  9% (2)
• D
  17% (4)

Explanation

Option B is correct because when clocks "fall back" in autumn, the 1:00 AM hour occurs twice - first in Daylight Saving Time (PDT, UTC-7) and again in Standard Time (PST, UTC-8). A timezone-aware cron scheduler fires at every wall-clock occurrence of the scheduled time, so it triggers once during each "version" of 1:00 AM.

Why A is wrong: Running once implies the scheduler skips the repeated hour, but most timezone-aware schedulers do not suppress duplicate wall-clock firings during fall-back.

Why C is wrong: Skipping entirely is what happens during spring-forward (e.g., a job at 2:30 AM is never reached when clocks jump from 2:00 to 3:00 AM) - the opposite transition from what's described here.

Why D is wrong: DST transitions are predictable, well-defined events; a properly configured timezone-aware scheduler handles them silently without errors.

Memory tip: Use the rhyme - "Spring forward, skip once; fall back, run twice." Associating the clock direction with whether a job is lost or duplicated makes DST cron behavior easy to recall under exam pressure.

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