If the domain master browser fails, the master browser for each network segment provides a browse list, containing only the servers in the local network segment. All servers that are not on the local network segment will eventually be removed from the browse list. Users will still be able to connect to servers on the other network segments 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. A BDC can perform most PDC network tasks, such as validating logon requests, but does not promote itself to PDC and does not become domain master browser in the event of a PDC failure.
Figure 3.6 Master browser failure