Edge telemetry aggregation
Design the telemetry pipeline for a global edge/CDN network: 300 points-of-presence, each handling 200k req/s, that need per-request metrics (status, latency, cache hit/miss, origin, customer) centralized for billing and analytics. Sending one event per request to a central system is 60M events/s — far too expensive. You still need accurate per-customer billing counters and the ability to investigate latency by customer/region/status. Design edge-side aggregation, what you keep raw vs aggregated, and how you bound central cardinality and cost.
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.
Clarify4:30 left
Estimate4:30 planned
Design13:30 planned
Deep dive10:30 planned
Failure7:00 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.