Centralized egress proxy
Design a centralized egress (forward) proxy that all outbound HTTP from a 5,000-service platform must route through, handling 60k outbound requests/sec to arbitrary third-party and customer-specified URLs. It must enforce an allow/deny policy (block internal IP ranges and metadata endpoints to prevent SSRF), apply per-destination rate limits and circuit breakers, reuse upstream connections for efficiency, and add under 5ms p99. Walk through the proxy architecture, the policy-enforcement model, and the central 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.
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.