CDNs and edge caching: how distributed delivery works

A CDN can serve cacheable content from distributed edge locations while keeping an origin behind the delivery layer. DNS, Anycast or provider-specific steering can select an edge; the IP seen by a user may therefore belong to the CDN rather than the origin.

How a CDN serves content from the edge

A CDN places copies of cacheable content on distributed edge nodes and selects a delivery point using DNS, Anycast or provider-specific steering. The IP visible to a user therefore often belongs to an edge node rather than the origin server.

How to check CDN caching

Inspect Cache-Control, Age and any CDN cache-status headers, then repeat the request and compare timing and HIT/MISS indicators. The public IP can belong to a CDN edge, so it does not necessarily reveal the origin server address. To separate domain data from the edge IP, cross-check it with 2ip domain information.

Why a CDN IP is not the origin address

Technical references: HTTP caching semantics in RFC 9111.