On-callMediumoc-g535

Subject Dependency authLevel Entry–Mid~20 minCommon in Security · Code quality & review interviewsIndustries Software development, Technology

Question

Your service's checkout flow suddenly fails. The dashboard shows that calls to a third-party payment provider are all returning HTTP 401 Unauthorized as of about 15 minutes ago. Your own service is up, other endpoints that don't call the provider are fine, and you didn't deploy anything. A teammate mentions the security team was 'rotating some secrets' this morning. How do you confirm and fix this?

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.