GISP: GIAC Information Security Professional Certification

A proxy server is designed to intercept and relay requests between internal clients and external services, effectively standing in for the client when communicating with the Internet. It can perform functions such as caching content, filtering requests, masking the client's IP address, and enforcing access policies — all characteristic of acting as an intermediary. In contrast, a firewall filters traffic based on security rules rather than acting as a go-between for service requests, while DNS and WINS servers merely perform name resolution and do not mediate communication sessions between clients and external services.