Shared key rate limit
Your platform sends notifications through a vendor (Twilio-style) using ONE shared API key for all your customers. At 13:00 a subset of your tenants report notifications delayed or dropped. Dashboards: the vendor returns a rising share of 429s with Retry-After; your total send rate to the vendor is at the per-key limit. One large tenant kicked off a bulk campaign at 12:55 that accounts for ~80% of current sends; smaller tenants' urgent messages (password resets) are stuck behind it in the same queue and same key. 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.