Authorization service
Design an authorization service that answers 'can user U do action A on resource R?' for a collaboration platform with 100M users and deeply nested resource hierarchies (orgs → teams → folders → documents) plus per-resource sharing. It must serve 1M authorization checks/sec at p99 under 10ms, reflect a permission change (e.g., a revoked share) within ~1s, and never return a false-allow. Discuss the data model, how you evaluate nested/inherited permissions at scale, and the consistency trade-off.
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.
Clarify5:30 left
Estimate5:30 planned
Design16:30 planned
Deep dive13:30 planned
Failure9:00 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.