A description of the automatic discovery feature

This article describes automatic discovery support for Firewall clients and Web Proxy clients in Microsoft Internet Security and Acceleration (ISA) Server 2000, in Microsoft ISA Server 2004, in Microsoft Forefront Threat Management Gateway Medium Business Edition, and in Windows Essential Business Server 2008.

ISA Server and Microsoft Forefront Threat Management Gateway Medium Business Edition use the Web Proxy Automatic Discovery (WPAD) protocol to automatically discover Web Proxy servers. The WPAD protocol lets clients locate a WPAD entry that contains a URL. This URL points to a server on which Wpad.dat and Wspad.dat files are generated. The Wpad.dat JScript file contains a default URL template that is constructed by Internet Explorer. Web Proxy clients use this script file to obtain information about automatic discovery. The ISA Server and Microsoft Forefront Threat Management Gateway, Medium Business Edition WinSock Proxy Autodetect (WSPAD) implementation uses the Wpad.dat file. This implementation creates a Wspad.dat file that provides information about automatic discovery to Firewall clients. For more information, visit the following Microsoft Web page: