The HTTP Age header indicates how long a specific object has been in a proxy’s cache.
The HTTP Age header is used to indicate the number of seconds that an object has been in a proxy cache. This is normally a very short duration. If the HTTP Age header is 0 then it was most likely retrieved from the origin server. Alternatively, it normally represents the difference between the proxy server’s date and the HTTP Date header included in the HTTP response.
In this example, the object has been in the cache for 15 seconds. The actual age is not reflected in this HTTP header.
The HTTP Age header is the number of seconds that an object has been cached in a proxy server and can be used to assess the staleness of the HTTP response.