When ISA server delivers the WPAD script or via dhcp, it sets a Cache-Control header with the value max-age=3000. Internet Explorer rounds this up to 1 hour. So, if you are testing WPAD changes, you will need to be sure to delete the previously acquired WPAD script.
- Clear the Internet Explorer cache completely
- del \wpad*.dat /s
- ipconfig /flushdns
- nbtstat -R