How does Rails handle distributed caching consistency across multi-region deployments?

Rails handles multi-region caching using Redis clusters, CDN caching, versioned keys, and event-driven invalidation.

In multi-region systems, cache consistency becomes complex due to replication lag and eventual consistency. Rails typically uses a combination of globally distributed caches (Redis Enterprise, AWS ElastiCache Global Datastore), CDN edge caching, and versioned cache keys (e.g., including timestamps or content hashes). Cache invalidation is often event-driven via message queues to ensure all regions invalidate or refresh stale entries. This avoids serving outdated data from different regions.