What device on a network acts as an intermediary between a client and server, evaluating requests according to specific rules?

A proxy server is a specific type of server that acts as an intermediary between clients and servers, processing requests made by clients and routing them to the appropriate server. When clients make requests for resources, such as web pages or files, the proxy server evaluates these requests based on predefined rules or policies. This could include assessing which requests to allow or deny, caching frequently requested resources to improve performance, and enhancing security by hiding the identity of the client making the request.

The role of a proxy server is crucial in various networking scenarios, such as improving web performance, implementing security features, and controlling access to specific content. By filtering traffic and managing requests, a proxy server can help balance loads, reduce bandwidth usage, and provide logging capabilities for monitoring and security purposes.

In contrast, other devices mentioned have different primary functions. A firewall primarily focuses on monitoring and controlling incoming and outgoing network traffic based on certain security rules, rather than acting as an intermediary for resource requests. A router directs data packets between different networks and manages traffic between them, while a switch connects devices within the same network and facilitates communication between them. Each of these devices serves important but distinct roles within a network.