Origin server Server on which a given resource resides or is to be created. Proxy Intermediary program which acts as both a server and a client for the purpose of making requests on behalf of other clients. Requests are serviced internally or by passing them on, with possible translation, to other servers. A proxy must implement both client and server requirements of HTTP 1.1 spec. Tags Product Tokens User-Agent and Server fields contain product tokens , which allow communicating applications to identify themselves by software name and version.
Most fields using product tokens also allow sub-products, separated by whitespace.
By convention, the products are listed in order of their significance for identifying the application. The value of the Via header field traces of request chain. Use of Max-Forwards header field allows client to limit request chain length. Useful for testing a chain of proxies forwarding messages in an infinite loop. Final recipient is either origin server or first proxy or gateway to receive a Max-Forwards value of zero in the request.