You can check which server you are using by scanning through the %windir%\WindowsUpdate.log
You should find a line that is along the lines of:
Server URL =
http://wsusservername/SimpleAuthWebService/SimpleAuth.asmxYou can use WSUS to patch servers in a different domain, as long as the remote server can connect to the WSUS server then it will work. WSUS is not tightly integrated to AD.
