A computer running Microsoft Windows NT involved in supporting the functions of the Computer Browser service.
A backup browser is a machine that obtains a copy of the browse list from the master browser. The browse list contains information about which shared resources are available to client machines on the network and about which domains are on the network. Backup browsers automatically contact the master browser every 12 minutes to request a copy of the browse list. If the contact is successful, the master browser issues the list to the backup browser. If the backup browser cannot contact the master browser, it starts a browser election to force a new master browser to be selected.
Once the backup browser has the browse list, it caches the list and distributes it to any client that requests it. To request the browse list from a backup browser, a client calls the NetServerEnum application programming interface (API) on the backup browser.
There will be one backup browser for every 32 systems in a given domain or workgroup on the network. The Computer Browser service determines the number of backup browsers necessary to ensure that clients can have efficient access to network resources.