What is a proxy server ?

A proxy server is an interface between your browser and the destination server. The proxy server will take your page request and handles for your browser the connection to the destination. These proxy servers are also able to cache pages. If such a proxy is configured to cache it will at first take look to its local cache if the requested page already exist. If not it can search in other caching proxy servers or makes directly the request to the destination. This depends on the configuration for the proxy.

The advantage of using a common caching proxy server is given by the probability to find a page in the local cache. The probability is in general expressed by the hit rate. A cache with several Gb size and a lot of users can reach a hit rate of 30 to 40 percent. Frequently requested pages for instance the help pages of your browser might be almost every time in the cache. In case that the page is not in the local cache you shouldn't see any difference in the elapsed time of a direct request or a request handled by a proxy server.