The most common use of the LMHOSTS file is to locate remote servers for file and print services. But the LMHOSTS file can also be used to find domain controllers providing domain services on routed TCP/IP networks. Examples of such domain controller activities include domain controller pulses (used for account database synchronization), logon authentication, password changes, master browser list synchronization, and other domain management activities.
Windows NT primary domain controllers (PDCs) and backup domain controllers (BDCs) maintain the user account security database and manage other network-related services. Because large Windows NT domains can span multiple IP subnets, it is possible that routers could separate the domain controllers from one another or separate other computers in the domain from the domain controllers. In a network that does not use WINS servers, LMHOSTS name resolution can be used to allow client computers to connect to domain controllers located across routers on different subnets.