Design a home timeline (Twitter/Instagram style) that shows recent posts from accounts a user follows.
How to approach it
Close by naming what breaks first under load, what you would cut under time pressure, and the one sentence that captures the system’s essence. Identifying the first bottleneck and the consistency/latency tradeoffs is the strongest senior signal you can give.
What breaks first
Fan-out write amplification when a high-follower account posts.
What to cut under pressure
- ranking (start chronological)
- media transcoding (separate service)
Remember
The whole problem is the read/write asymmetry; the hybrid fan-out is the senior-signal answer.