I’ve talked about changes in how DNS works with updates to Windows Server 2003 and Windows Server 2008 as they relate to WPAD. The main reason I’ve brought this topic up in the past is that I got burned with strange WPAD failures.
Even when I had configured a WPAD Host (A) record on the Windows Server 2008 DNS server and configured the ISA firewall to published autodiscovery information, the autodiscovery process failed. When troubleshooting the problem with NetMon 3.x, I found that the DNS server was responding with “server failure” messages, in spite of the fact that there was a WPAD entry in the domain.
Richard Hicks puts his own spin on this issue on his blog at http://tmgblog.richardhicks.com/2009/06/16/dns-security-enhancements-and-web-proxy-auto-discovery/
Take a read of Richard’s article and keep this issue in mind the next time your autodiscovery process failure. It just might be a DNS issue.
Thomas W Shinder, M.D., MCSE
Sr. Consultant / Technical Writer