On-callHardoc-p036

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

Question

After a scheduled key/certificate rotation, services started failing to authenticate to each other — mutual TLS or token validation is rejecting valid callers. How do you respond?

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.