Cache miss thundering herd
Your read path is normally a 2ms cache hit, but a few times an hour p99 spikes to 1.5s and the origin database briefly sees a 50x read burst, then everything returns to normal. The bursts line up exactly with the TTL boundary of one very hot cache key (a global config/leaderboard blob with a fixed 5-minute TTL). The cache and DB are otherwise healthy and there was no traffic change. How do you 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 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.