Microsoft has enabled enforcement mode for updates addressing the Windows Zerologon vulnerability on all devices that installed this month’s Patch Tuesday security updates. Zerologon is a critical Netlogon Windows Server process security flaw (tracked as CVE-2020-1472) that allows attackers to elevate privileges to domain administrators and take control over the domain following successful exploitation. The only exception applies to DCs manually added by admins to a dedicated security group which allows vulnerable NetLogon secure channel connections.
Source: https://www.bleepingcomputer.com/news/security/microsoft-now-forces-secure-rpc-to-block-windows-zerologon-attacks/