"Tell me about debugging a production issue."
Your interviewer wants to see your process:
Assess impact: What's broken? Who's affected? How urgent?
Communicate: Notify stakeholders. Set expectations.
Investigate systematically: Check recent changes. Review logs. Isolate the failure point.
Fix or mitigate: Sometimes a quick fix buys time. Sometimes you need a proper solution.
Document and prevent: Postmortem. What failed? Why? How to prevent?
Show calm under pressure. Methodical approach beats panic.