The following rules determine the number of browsers in a domain or workgroup. In this discussion, the words domain and workgroup are used interchangeably.
If there is currently a PDC in the domain, it will be the master browser for the domain.
Every BDC in the domain will be a backup browser for the domain. The only exception to this is if the BDC is needed as a master browser because the PDC has failed. In that case, the BDC will be the master browser for the domain.
If a computer's MaintainServerList registry parameter is set to Yes, this computer will be a backup browser for the domain or TCP/IP subnet.
If no backup browsers are selected for the domain based on the preceding rules, the master browser determines the number of backup browsers for the domain. If a computer's MaintainServerList registry parameter is set to Auto, the master browser will select some of those computers to act as backup browsers based on the number of computers in the domain.
Table 3.3 Number of browsers in a domain or workgroup
| Number of Backup Browsers | Number of Master Browsers |
1 | 0 | 1 |
2 to 31 | 1 | 1 |
32 to 63 | 2 | 1 |
For each additional 32 computers added to the domain, another backup browser is selected for the domain.
For the TCP/IP transport, each subnet independently enforces the preceding set of rules.