Queue throttling synchronous path
Your order pipeline enqueues every order event into a managed message queue (SQS-style). At 15:00 your order-API p99 jumps from 120ms to 4s and ~10% of orders fail. Dashboards: SendMessage calls to the queue are returning throttling errors ('RequestThrottled' / 429) and high latency; the queue's API request rate hit a soft account limit after a promo doubled order volume. Your API enqueues synchronously inside the request path and retries the send up to 3 times before failing the order. Your own service CPU/DB are healthy. 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 30 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.