If you need to know where your client machine points to for it’s windows updates via registry, follow below instructions.

Please note:
Modifying the Windows registry can be dangerous. Incorrectly modifying the registry can destroy your operating system, applications or data. I therefore highly recommend that you perform a full system backup prior to attempting any of the techniques on this website.

1) Launch registry
2) Browse to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate
3) The Windows Update server name can be located within the registry name WUServer