Origin servers saturate
Your origin servers suddenly see a 5x jump in request rate and CPU saturation, with origin latency climbing and some 5xx errors, even though end-user traffic (requests hitting the CDN) is flat. CDN dashboards show the cache hit ratio dropped from ~96% to ~70% over 30 minutes, and origin-facing requests spiked. A deploy 40 minutes ago changed how the app sets cache headers and added a request-correlation query parameter to asset URLs for tracing. An 'origin shield' tier sits between edge POPs and origin. Triage and fix.
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.