System designHardsd-g050

Subject Reverse proxyLevel Senior–Staff~40 minCommon in Distributed systems interviewsIndustries Technology, Software development

Question

Design a reverse proxy / API gateway sitting in front of ~300 internal microservices handling 1M req/s. It must pool upstream connections, apply per-route timeouts and retries, and shed load when a downstream is slow without taking down the whole gateway. A single slow dependency currently causes the whole gateway to run out of threads. Explain the architecture and how you prevent one bad backend from cascading.

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.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.