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HTTP Caching

Trace how one response moves through cache key lookup, freshness checks, validation, Vary splitting, and immutable asset reuse.

Browserprivate cache/guide90s oldemptyEdge cacheshared cache/guideETag: "build-19f3a2"emptyAge + Cache-Control decide freshnessOriginpolicy sourceCache-Control: publicETag + freshness headersorigin decides policy, caches enforce it
Step 1 / 6The first request is always a miss

No cache can answer until someone asks for the object once. The browser and the edge both need the first response headers before they can make reuse decisions.

Browser -> edge -> origin

Client encoding for the request key

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