Production Backend Patterns Questions

Covers common server side patterns used to make real systems resilient and performant in production. Topics include rate limiting algorithms such as token bucket and sliding window, caching strategies and eviction policies such as least recently used and least frequently used, cache invalidation approaches, retry semantics with exponential backoff and jitter, circuit breaker and bulkhead patterns, idempotency design, and trade offs between latency, throughput, and cost. Candidates should be prepared to explain failure modes, monitoring needs, testing approaches, and how to choose patterns based on workload and correctness requirements.