You could pick a machine in each site and run from command prompt:
reg query "HKLM\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" /s
you could even(if you familiar) use psexec to do it remotely.
psexec \\computername -c-f-s \\server\share\regquery.bat <<
psexec \\* <<
psexec @list.txt <<