Distributed Systems Design and Scalability Questions

Evaluate the ability to design distributed systems that satisfy high concurrency, low latency, and strong availability requirements. Topics include partitioning and sharding strategies, caching architecture and invalidation, load balancing and traffic management, data replication and consistency models, failure detection and recovery patterns, idempotency and retry semantics, back pressure and flow control, stateful versus stateless design, capacity planning and benchmarking, and operational practices for running at scale. Candidates should discuss measurable goals, tradeoffs between consistency and availability, and concrete techniques to mitigate real world failure scenarios.