Retry amplification cascade
A request flows A → B → C. C has intermittently slow calls (its p99 is 6s). A's client timeout to B is 2s with 2 retries; B's client timeout to C is 5s with 2 retries. When C is slow, you observe: A times out at 2s and retries, but B is still happily working on the first request (and will keep going up to 5s × retries), and the backend ends up doing far more work for C than the user ever waits for. C's load climbs even though user traffic is flat. Triage and explain the timeout/retry misconfiguration.
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.