Orders charged twice
Your order-processing consumer reads from Kafka and writes to Postgres. At 13:00 finance reports some orders are charged twice. Dashboards: the consumer group rebalanced at 12:58 (a pod was OOM-killed and restarted); consumer lag briefly spiked then recovered; you commit Kafka offsets AFTER processing each message; the charge call to the payment provider and the DB insert are separate steps with no shared transaction. No code deploy. 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.
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.