On-callMediumoc-g067

Subject Dependency outagesLevel Mid–Senior~30 minCommon in Reliability & on-call · Code quality & review interviewsIndustries Technology, Software development

Question

It's a Tuesday afternoon and your checkout service's p99 latency jumps from 180ms to 9s. Error rate on /checkout climbs to 22%. Dashboards show your payment provider's API (Stripe charge creation) returning a mix of HTTP 503s and connections that hang until your 10s client timeout fires. Your own CPU, memory, and DB metrics are flat-to-low. There was no deploy in the last 6 hours. The Stripe status page just flipped one component to 'degraded.' Inbound checkout traffic is normal for the time of day. How do you triage and mitigate?

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.