Debug HTTP header for Azure CDN from Microsoft

The debug response header, X-Cache, provides details as to what layer of the CDN stack the content was served from. This header is specific to Azure CDN from Microsoft.

Response header format

Header	Description
X-Cache: TCP_HIT	This header is returned when the content is served from the CDN edge cache.
X-Cache: TCP_REMOTE_HIT	This header is returned when the content is served from the CDN regional cache (Origin shield layer)
X-Cache: TCP_MISS	This header is returned when there is a cache miss, and the content is served from the Origin.
X-Cache: PRIVATE_NOSTORE	This header is returned when the request cannot be cached as Cache-Control response header is set to either private or no-store.
X-Cache: CONFIG_NOCACHE	This header is returned when the request is configured not to cache in the CDN profile.
X-Cache: N/A	This header is returned when the request that was denied by Signed URL and Rules Set.

For additional information on HTTP headers supported in Azure CDN, see Front Door to backend.