System Design and Scalability Questions

Covers architectural thinking and design tradeoffs for building reliable, high performance systems. Topics include design decision reasoning given constraints such as cost, latency and availability; scaling strategies including horizontal and vertical scaling, load balancing, caching patterns, database partitioning and sharding, read replicas, and asynchronous processing; capacity planning and observability; spotting and explaining bottlenecks such as hot partitions, single points of failure, database locks and network limits; and communicating technical impact in business terms. Candidates should be able to justify choices, compare alternatives, and articulate metrics and monitoring approaches to validate design decisions.