Design a read-heavy system

Design a system that must serve [N] reads per second for [Data Type] where reads vastly outnumber writes. Propose a layered stack combining a primary database, a distributed read cache, a CDN for static or semi-static data, and read replicas for database-level fan-out. Define the consistency model and acceptable staleness for each layer. Describe the cache invalidation strategy for each layer when data changes. Explain how the system behaves during a cache stampede on a popular key under spike traffic and what monitoring signals indicate the read path is healthy.