Edge feature-flag evaluation
Design feature-flag / A-B-test evaluation at the edge: 200 PoPs each must evaluate flags for every request with near-zero latency (no central call per request), yet flag changes from a central config service must roll out globally within ~30 seconds, and a user must get a stable, consistent variant (not flip between variants on consecutive requests routed to different PoPs). Design the config distribution, the local evaluation model, and how you guarantee per-user variant stability across PoPs.
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.