References from Windows IT Pro Center

1. AD DS Troubleshooting (https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/manage/ad-ds-troubleshooting)
2. Top support solutions for Windows Server 2016 (https://docs.microsoft.com/en-us/windows-server/troubleshoot/windows-server-support-solutions)
3. WSUS Messages and Troubleshooting Tips (https://docs.microsoft.com/en-us/windows-server/administration/windows-server-update-services/manage/wsus-messages-and-troubleshooting-tips)