Overview#Web Proxy Auto-Discovery Protocol (WPAD) is an Internet Draft that describes a Discovery Mechanism and protocol for nearby web Proxy Server caches by User-agents (i.e Browsers) .
Web Proxy Auto-Discovery Protocol even though "Expired" (December 1999) is still widely used.
Current best practice is for end users to hand configure their web client (i.e., browser) with the URL of an "auto configuration file". In large environments this presents a formidable support problem. It would be much more manageable for the web client software to automatically learn the configuration information for its web proxy settings. This is typically referred to as a resource discovery problem.
Web client implementers are faced with a dizzying array of resource discovery protocols at varying levels of implementation and deployment. This complexity is hampering deployment of a "web proxy auto-discovery "facility. This document proposes a pragmatic approach to web proxy auto-discovery. It draws on a number of proposed standards in the light of practical deployment concerns. It proposes an escalating strategy of resource discovery attempts in order to find a nearby web proxy server. It attempts to provide rich mechanisms for supporting a complex environment, which may contain multiple web proxy servers.Proxy Auto-Config are subject to malicious PAC Attacks