Cache Invalidation Explained

Cache invalidation is how you ensure users don’t keep receiving stale content after you deploy an update. Without invalidation, a CDN might continue serving an older cached copy until its TTL expires.

There are a few common strategies: short TTLs (simple but less efficient), versioned URLs (best for static assets), and explicit purges (invalidate specific paths or patterns when you publish changes).

The goal is to balance freshness and performance: invalidate only what changed, keep stable assets cached for a long time, and use predictable versioning so new content is fetched immediately.