Useful methods how to determine if WSUS is used in corporate environment.
- Locate WSUS via registry key called WUServer on client/server inside: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\
- Locate file c:\windows\windowsupdate.log where should be WSUS server url
- Run Gpedit.msc > Computer Configuration > Administrative Templates > Windows Components > Windows Update > Specify intranet Microsoft Update Service Location
- From Domain Controller you can run Group Policy Results on specific machine or run rsop.msc directly on specific machine.