Retry amplification during vendor outage
Your account-onboarding API (Node.js) depends on a third-party KYC/identity-verification vendor over HTTPS. At 11:20 the vendor starts returning HTTP 503 for ~30% of calls and timing out on another ~20%. Your onboarding 5xx rate jumps to 50% and your own p99 doubles. The vendor's status page is green. Your retry layer is configured to retry up to 3 times on 5xx/timeout with no backoff. As you watch, the vendor's failure rate gets *worse*. Triage and mitigate, and explain the dynamic you're likely contributing to.
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.
0:00 of about 35 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.