Domain Master Browser Failures
If the domain master browser fails, the master browser for each network subnet provides a browse list, containing only the servers in the local network subnet. All servers that are not on the local network subnet are eventually removed from the browse list. Even after the servers are removed, users are still able to connect to servers on the other network subnets if they know the name of the server.
Because a domain master browser is also a PDC, an administrator can correct the failure by promoting a BDC to PDC; this causes the DOMAIN[IB] record to be updated in WINS. A BDC can perform most PDC network tasks, such as validating logon requests, but it does not promote itself to PDC and does not become the domain master browser in the event of a PDC failure. Figure I.6 shows events in a Master Browser failure.
Figure I.6 Master Browser Failure