I use squid as a reserve Proxy with cache. When squid has a resource cached it doesn't send a request to http server to check if the resource is modified. I want to know if is possible (and how) to do: * Squid send a request to http server asking if the resource is modified. * If the http server doesn't answer, squid uses the cached object. (Very important) * If the http server answers that the resource is modified, squid gets the new resource, if not, it uses the cached object.
