WPAD is a protocol that allows a device to automatically discover and configure the appropriate proxy server for a network without manual setup, typically by querying a specially named DNS or DHCP record for a configuration file. It is primarily used in enterprise and managed-network environments where IT administrators want every device on the network routed through the same proxy without configuring each one by hand.

WPAD has a well-documented history of security issues, as a misconfigured or spoofed WPAD response can silently redirect a device's traffic through an attacker-controlled proxy. This is why US-CERT has advised disabling automatic proxy discovery unless systems are used solely on internal networks.