In-flight requests lost
You flip a payment-processing API from blue to green at 14:00 by switching the LB target group, then immediately scale blue to zero. Green is healthy. But over the next hour, reconciliation flags ~200 payments stuck in 'PROCESSING' that never reached a terminal state. These all correspond to requests that were in flight on blue at 14:00. Blue handled an async finalize step a few seconds after the initial response. Triage, explain the failure, and describe how to recover and prevent it.
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 40 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.