System Design: Distributed Caching System

Designing a distributed caching system is a common system design interview question that tests your ability to think about scalability, reliability, and performance. This guide walks through a complete design covering requirements gathering, high-level architecture, detailed component design, and scaling strategies.

Start by clarifying both functional and non-functional requirements. Functional requirements define what the system does: the core features that users interact with directly. Non-functional requirements define how the system behaves: availability targets, latency budgets, throughput expectations, and data consistency guarantees. For this system, we target 99.99 percent availability, sub-100ms latency for read operations, and the ability to handle millions of requests per day.