Azure CDN Cache Status Codes

Article
07/07/2016

Applies To: Microsoft Azure

This topic lists the cache status codes available when configuring Azure CDN Real-Time Statistics or Real-Time Alerts. For more information on Azure CDN features, see the Azure CDN Overview.

Cache Status Code	Description
CONFIG_NOCACHE	This status indicates that a customer-specific configuration on our edge servers prevented the asset from being cached. For example, an HTTP Rules Engine rule can prevent an asset from being cached by enabling the Bypass Cache feature for qualifying requests.
NONE	This status indicates that a cache content freshness check was not performed. This check is skipped when Token-Based Authentication denies a request or when an HTTP request method is used that bypasses cache (e.g., PUT, DELETE, etc).
TCP_CLIENT_REFRESH_MISS	This status is reported when an HTTP client (e.g., browser) forces an edge server to retrieve a new version of a stale asset from the origin server. By default, our servers prevent an HTTP client from forcing our edge servers to retrieve a new version of the asset from the origin server. However, this behavior can be overridden through the use of the HTTP Rules Engine feature called "Honor No-Cache Request."
TCP_EXPIRED_HIT	This status is reported when a request that targeted an asset with an expired time to live (TTL), such as when the asset's max-age has expired, was served directly from the POP to the client. An expired request typically results in a revalidation request to the origin server. In order for a TCP_EXPIRED_HIT to occur, the origin server must indicate that a newer version of the asset does not exist. This type of situation will typically update that asset's Cache-Control and Expires headers.
TCP_EXPIRED_MISS	This status is reported when a newer version of an expired cached asset is served from the POP to the client. This occurs when the TTL for a cached asset has expired (e.g., expired max-age) and the origin server returns a newer version of that asset. This new version of the asset will be served to the client instead of the cached version. Additionally, it will be cached on the edge server and the client.
TCP_HIT	This status is reported when a request is served directly from the POP to the client. An asset is immediately served from a POP when it is cached on the POP closest to the client and it has a valid TTL. TTL is determined by the following response headers: `Cache-Control: s-maxage` `Cache-Control: max-age` `Expires`
TCP_MISS	This status indicates that a cached version of the requested asset was not found on the POP closest to the client. The asset will be requested from either an origin server or an origin shield server. If the origin server or the origin shield server returns an asset, it will be served to the client and cached on both the client and the edge server. Otherwise, a non-200 status code (e.g., 403 Forbidden, 404 Not Found, etc.) will be returned.
TCP_PARTIAL_HIT	This status is reported when a request results in a hit for a partially cached asset. The requested asset is immediately served from the POP to the client.
UNCACHEABLE	This status is reported when an asset's Cache-Control and Expires headers indicate that it should not be cached on a POP or by the HTTP client. These types of requests are served from the origin server.