For caching components (e.g. apache mod_cache) which are installed in front of a webapplication having configured the GZipFilter, the http-response needs to contain the http header "Vary: Accept-Encoding" - indicating that the response differs depending on the request-header "Accept-Encoding".
No matter whether the response was zipped or not, the response-header "Vary: Accept-Encoding" should be included.
For caching components (e.g. apache mod_cache) which are installed in front of a webapplication having configured the GZipFilter, the http-response needs to contain the http header "Vary: Accept-Encoding" - indicating that the response differs depending on the request-header "Accept-Encoding".
No matter whether the response was zipped or not, the response-header "Vary: Accept-Encoding" should be included.
See also https://www.fastly.com/blog/best-practices-for-using-the-vary-header