You put a cache in front of a heavy database query. What problems do you expect with this cache under high load, and how will you solve them?
~4 min by voice
How to approach it
They're checking whether the candidate understands that a cache is a distributed system with its own failure modes. You need to see the correctness problems (stale data, races during invalidation) and the load problems (stampede, hot keys, the cache going down), and be able to close them systematically.
The interviewer will ask this question and listen. Think out loud and ask for a hint if you need one. When you're done, pause or tap “That's my answer”. In about a minute, your score and the points you covered show up here.