primary domain:

LookupAccountName

Enumerating network resources

Enumerating servers of the specified type (e.g. SQL Server) in the primary domain

How to enumerate, add and delete shares on the local computer (WinNT/XP)

Retrieving the name of the primary domain controller (PDC) and join status information (NT/2000/XP)

Using mailslots to send messages on the network