If WINS is not configured and there is no entry in LMHOSTS then the Workstation will send out a series of 3 broadcasts.
In the situation where no response is received and WINS is configured to use DNS for WINS resolution a request to the DNS server will be sent and finally the HOSTS file checked.
Another Note: Microsoft has a nice tool called Dumpfsmos.cmd, found in the Windows 2000 Resource Kit (and can be downloaded here: Download Free Windows 2000 Resource Kit Tools).
This tool is basically a one-click Ntdsutil script that performs the same operation described above.
When a logon request is made to a domain, the workstation sends out a request to find a domain controller for the domain.
But Replmon can also provide valuable information about the AD, about any DC, and also about other objects and settings, such as GPOs and FSMO roles.
Install the package before attempting to use the tool.
The transferring method is described in the Transferring FSMO Roles article, while seizing the roles from a non-operational DC to a different DC is described in the Seizing FSMO Roles article.
In order to better understand your AD infrastructure and to know the added value that each DC might possess, an AD administrator must have the exact knowledge of which one of the existing DCs is holding a FSMO role, and what role it holds.