Because the browser service relies on server broadcasts, its communication is connectionless and by definition unreliable. When a server starts, it immediately sends a host announcement frame. This process is repeated at 4 minutes and again at 8 minutes. The process is then repeated every 12 minutes thereafter.
Allowing for the loss of a few datagram frames, it is reasonable to expect that the network segment's master browser will add a given computer's name to the browse list within 12 minutes after startup. Beyond this point, connection-oriented traffic is used and the sequences are more deterministic. Within 12 minutes, the segment's master browser will connect to the PDC to obtain the domain-wide list, and at the same time the PDC will connect to the master browser and learn of the new server.
Master browsers on remote segments also connect to the PDC at 12-minute intervals and soon learn of a new server. Within 12 minutes of the remote master browser learning of a new computer's name, all the backup browsers connect to their master browser. At this point, all browsers on a remote segment know about the new server. In a multi-segment WAN environment, the maximum amount of time it should take for all clients within the domain to see the new computer is 48 minutes (12 + 12 + 12 + 12). On a network on which broadcasts and network usage are well within safe parameters, this period should average approximately one-half as long (24 minutes).
Removing computers from the browse list may take more time. To allow for lost datagram frames, the master browser does not remove a server from its list until 3 announcement periods have passed. If the server is not shut down gracefully or if network connectivity is lost, the server can remain in the master browser's list for up to 36 minutes. After this time, the PDC is notified to remove the server name. The same communication flow follows to remove a server's name. Within 12 minutes, a master browser on a remote segment obtains the domain-wide list from the PDC, and within 12 minutes each backup browser connects to the master browser. This process can take as long as 72 minutes to finish (36 + 12 + 12 + 12). If the server is shut down gracefully, the browser sends a single Host Announcement frame indicating that it is no longer acting as a server. Upon receipt of this datagram, the master browser immediately removes the server from its local list. On a network on which broadcasts and network usage are well within safe parameters, this period should average approximately one-half as long (36 minutes).
Because a server's browser role is defined dynamically with periodic elections, determining the flow of communication used to provide the browse list to a specific client computer can be difficult. If a master browser is shut down gracefully, the master browser forces an election for a new master browser during shutdown. If the backup browser that wins the election has been present on the network long enough to receive a complete browse list, it starts as a master browser with a fully populated browse list, and browse functionality continues on the network segment without interruption.
If a server that was acting as the master browser is not shut down gracefully or if the master browser's force election request datagram is lost, there may be a delay before browse functionality is available on the network segment. An election of a new master browser is caused if a client computer requests a browse list and is unable to locate a master browser. It may take up to 12 minutes for a backup browser to discover that no master browser is present, depending on network usage.
Source:http://www.compinfo.co.uk/
Allowing for the loss of a few datagram frames, it is reasonable to expect that the network segment's master browser will add a given computer's name to the browse list within 12 minutes after startup. Beyond this point, connection-oriented traffic is used and the sequences are more deterministic. Within 12 minutes, the segment's master browser will connect to the PDC to obtain the domain-wide list, and at the same time the PDC will connect to the master browser and learn of the new server.
Master browsers on remote segments also connect to the PDC at 12-minute intervals and soon learn of a new server. Within 12 minutes of the remote master browser learning of a new computer's name, all the backup browsers connect to their master browser. At this point, all browsers on a remote segment know about the new server. In a multi-segment WAN environment, the maximum amount of time it should take for all clients within the domain to see the new computer is 48 minutes (12 + 12 + 12 + 12). On a network on which broadcasts and network usage are well within safe parameters, this period should average approximately one-half as long (24 minutes).
Removing computers from the browse list may take more time. To allow for lost datagram frames, the master browser does not remove a server from its list until 3 announcement periods have passed. If the server is not shut down gracefully or if network connectivity is lost, the server can remain in the master browser's list for up to 36 minutes. After this time, the PDC is notified to remove the server name. The same communication flow follows to remove a server's name. Within 12 minutes, a master browser on a remote segment obtains the domain-wide list from the PDC, and within 12 minutes each backup browser connects to the master browser. This process can take as long as 72 minutes to finish (36 + 12 + 12 + 12). If the server is shut down gracefully, the browser sends a single Host Announcement frame indicating that it is no longer acting as a server. Upon receipt of this datagram, the master browser immediately removes the server from its local list. On a network on which broadcasts and network usage are well within safe parameters, this period should average approximately one-half as long (36 minutes).
Because a server's browser role is defined dynamically with periodic elections, determining the flow of communication used to provide the browse list to a specific client computer can be difficult. If a master browser is shut down gracefully, the master browser forces an election for a new master browser during shutdown. If the backup browser that wins the election has been present on the network long enough to receive a complete browse list, it starts as a master browser with a fully populated browse list, and browse functionality continues on the network segment without interruption.
If a server that was acting as the master browser is not shut down gracefully or if the master browser's force election request datagram is lost, there may be a delay before browse functionality is available on the network segment. An election of a new master browser is caused if a client computer requests a browse list and is unable to locate a master browser. It may take up to 12 minutes for a backup browser to discover that no master browser is present, depending on network usage.
