On-callHardoc-p033

Subject Incident responseLevel Senior–Staff~20 minCommon in Reliability & on-call interviewsIndustries Technology

Question

No errors are firing, but support reports users seeing wrong values (prices or balances look off). You suspect a dependency started returning subtly incorrect data. How do you investigate?

What a strong answer looks like

Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.

Learn the concepts

Diagram & narrate the incident

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Run or narrate your approach, then ask the coach.