What type of server acts as a mediator between a client and an external server?

• A. DNS server
• B. Firewall
• C. Caching server
• D. Proxy

Answer: (D)

A proxy server sits between the client and the external server, acting as the intermediary for requests and responses. When a client requests a resource, that request goes to the proxy, which then forwards it to the external server. The external server’s response goes back through the proxy to the client. This setup allows the proxy to apply policies, filter content, anonymize the client, or cache responses to speed up future requests.

DNS servers simply translate domain names to IP addresses and don’t relay application data between client and server. A firewall sits at the network edge to allow or block traffic based on rules rather than mediating the actual content exchange. A caching server stores copies of resources to speed future access but is not by itself the mediator for each client request; caching is a feature that proxies can provide.