Media upload and abuse screening
Design the upload + validation pipeline for a public user-generated image/video host (think Imgur) accepting anonymous and authenticated uploads at 20K uploads/sec. Uploads must be validated (real media of the claimed type, within size limits), screened for abuse (CSAM/NSFW/malware), and made available quickly, but a malicious user must not be able to exhaust storage, smuggle a non-media payload, or get illegal content served even for a moment. Design the ingest path, validation ordering, and abuse defenses.
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.
Clarify4:00 left
Estimate4:00 planned
Design11:30 planned
Deep dive9:30 planned
Failure6:00 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.