## Question Tell me about a problem whose root cause you identified yourself. Explain the initial symptom, competing hypotheses, evidence collected, the actual causal chain, the fix, and how you proved both recovery and prevention. ### Constraints & Assumptions - Choose an example where diagnosis required more than reading an obvious error message. - Preserve the difference between the triggering event, the root cause, and contributing conditions. - Do not reveal confidential identifiers or claim measurements you cannot support. - Include one hypothesis you rejected and why. ### Clarifying Questions to Ask - Would you prefer a production incident, a recurring defect, or a development-system problem? - How much low-level diagnostic detail would be useful? - Should I emphasize the investigation or the prevention work? ```hint Build a causal timeline Connect symptom, evidence, mechanism, and impact in order. A correlation becomes a root cause only when the mechanism and fix are validated. ``` ### What a Strong Answer Covers - A precise symptom and impact boundary. - Evidence-driven narrowing rather than random changes. - A causal explanation that distinguishes root cause and contributing factors. - Safe mitigation, permanent correction, and verification. - A prevention change in tests, monitoring, process, or architecture. ### Follow-up Questions 1. Which signal was misleading? 2. How did you avoid making the incident worse while testing hypotheses? 3. What evidence would have falsified your final diagnosis? 4. Has the failure recurred?