X-Cache
Indicates whether the request was a HIT or a MISS.
Fastly writes this header into responses. It is proprietary to Fastly.
Fastly appends this non-standard header to all responses by default, using a simplified derivative of the value of thefastly_info.state variable. If the value offastly_info.state isHIT or any value that starts withHIT- thenX-Cache will be set toHIT, otherwiseMISS.
Requests resulting in a PASS will be reported asMISS, while requests resulting in edge-generated synthetic content will be reported asHIT. Additionally all hits resulting from serving stale or background revalidations will also report asHIT.
This header may contain reports from multiple servers, ifshielding orNext-gen WAF at Edge is enabled, or if you use custom VCL code that invokes therestart statement.
Other than in the case of arestart, any entries in this header except "MISS" indicate that the request was satisfied from cache and not forwarded to origin (or Next-gen WAF at Edge)
You can remove this header, or make it subject toFastly-Debug, by using VCL in thevcl_deliver subroutine (after the#FASTLY deliver placeholder in custom VCL, or in a 'deliver' VCL snippet):
if (!req.http.Fastly-Debug) { unsetresp.http.X-Cache;}