Do not use NetBIOS-based discovery for domain controller location when DNS-based discovery fails

This policy setting allows you to control the domain controller (DC) location algorithm. By default, the DC location algorithm prefers DNS-based discovery if the DNS domain name is known. If DNS-based discovery fails and the NetBIOS domain name is known, the algorithm then uses NetBIOS-based discovery as a fallback mechanism. NetBIOS-based discovery uses a WINS server and mailslot messages but does not use site information. Hence it does not ensure that clients will discover the closest DC. It also allows a hub-site client to discover a branch-site DC even if the branch-site DC only registers site-specific DNS records (as recommended). For these reasons, NetBIOS-based discovery is not recommended. Note that this policy setting does not affect NetBIOS-based discovery for DC location if only the NetBIOS domain name is known. If you enable or do not configure this policy setting, the DC location algorithm does not use NetBIOS-based discovery as a fallback mechanism when DNS-based discovery fails. This is the default behavior. If you disable this policy setting, the DC location algorithm can use NetBIOS-based discovery as a fallback mechanism when DNS based discovery fails. This setting has no effect unless the BlockNetbiosDiscovery setting is disabled. NetBIOS-based discovery is considered unsecure, has many limitations, and will be deprecated in a future release. For these reasons, NetBIOS-based discovery is not recommended. See https://aka.ms/dclocatornetbiosdeprecation for more information.