After a Active Directory migration to Windows 2008 (R2) the “automatically detect settings” setting in your browser can stop working. The reason for this isn’t that obvious and you can spend a lot of time looking for a solution. First a little explanation how this principle works. When “automatically detect settings” is enabled the browser will search for a file called WPAD.DAT located on a webserver called wpad.yourdomain;. To resolve this address a CNAME WPAD must be present in DNS.
To see if the global query block list is enabled use the following command: dnscmd /info /enableglobalqueryblocklist
Listing which hosts are blocked can be done by: dnscmd /info /globalqueryblocklist
To resolve the issue and remove the block use the following command: dnscmd /config /enableglobalqueryblocklist
Now the proyx settings should be detected again and browsing will work!