Web Proxy Auto-Discovery Protocol (WPAD) is a recommended Internet protocol that allows clients (such as web browsers or streaming media applications) to automatically locate and interact with cache services on the network, thereby Can deliver information to users faster. Caching services store copies of popular web pages close to users, usually on the outer edge of the network for faster access. When a specific page is requested, the browser is directed to the caching service of that page, rather than having to reach the originating site through the network.
The caching service is maintained and provided by Internet service providers (ISP) and special caching services (such as Akamai). The first browser to support WPAD is Internet Explorer 5.0. WPAD is a joint effort of Inktomi, Microsoft, Real Networks and Sun Microsystems.
When an Internet session is started, a WPAD-enabled client will automatically use the Dynamic Host Configuration Protocol (DHCP) to find the cache service. If unsuccessful, WPAD uses the Service Location Protocol (SLP). SLP is a protocol that allows network applications to discover the location and configuration of network services in an enterprise. If it is still unsuccessful, WPAD will search for Domain Name System (DNS) records. Once a nearby cache service is found, WPAD will automatically connect to that location to obtain related page requests.