Activity feed
Design a basic activity feed for a small social app (think a few thousand users). Each user follows some others, and their home feed shows recent posts from the people they follow, newest first. Posting is far less frequent than reading the feed. Describe your data model and how you build a user's feed.
What a strong answer looks like
Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts (data model, bottlenecks, consistency, failure modes) and name the trade-offs you are making.
Clarify3:30 left
Estimate3:30 planned
Design10:00 planned
Deep dive8:00 planned
Failure5:00 planned
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.