Debug HTTP header for Azure CDN from Microsoft

Important

Azure CDN Standard from Microsoft (classic) will be retired on September 30, 2027. To avoid any service disruption, it's important that you migrate your Azure CDN Standard from Microsoft (classic) profiles to Azure Front Door Standard or Premium tier by September 30, 2027. For more information, see Azure CDN Standard from Microsoft (classic) retirement.

Azure CDN from Edgio was retired on January 15, 2025. For more information, see Azure CDN from Edgio retirement FAQ.

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's a cache miss, and the content is served from the Origin.
X-Cache: PRIVATE_NOSTORE This header is returned when the request can't 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 a request gets denied by Signed URL and Rules Set.

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