Which statement best describes a proxy server's function?

• A. A server that stores and indexes documents.
• B. A server that handles DNS queries only.
• C. A server that assigns IP addresses to devices.
• D. A server that acts as an intermediary between an internal network and the Internet.

Answer: (D)

A proxy server acts as an intermediary between internal systems and the Internet. When a client on the internal network requests something from the Internet, the proxy forwards that request on behalf of the client, receives the response, and sends it back to the client. This arrangement lets administrators enforce security policies, monitor and log traffic, filter or block unwanted content, and sometimes cache popular resources to improve performance. It also helps keep internal systems from being exposed directly to external networks.

Storing and indexing documents describes a search or repository server. Handling DNS queries only describes a DNS resolver or DNS server. Assigning IP addresses to devices describes a DHCP server. Those roles are distinct from the proxy’s function as a traffic intermediary between the internal network and the Internet.