How does Rails implement multi-layer caching strategies in high-scale systems?

Rails uses a combination of browser cache, CDN, application cache, and database cache to reduce latency and load.

Multi-layer caching in Rails is designed to reduce redundant computation at every layer of the stack. Browser caching handles static assets, CDNs cache edge responses, Rails fragment and low-level caches store computed views or objects, and DB query caching reduces repeated SQL execution. Cache invalidation strategies often rely on versioned keys or event-driven invalidation. The challenge is maintaining consistency across layers while avoiding stale data propagation.