When a computer is started, it announces itself by sending a server announcement to the domain or workgroup's master browser every minute. As the computer continues running, the time between server announcements is increased until it eventually becomes once every 12 minutes.
If the master browser has not received a server announcement from a computer for three announcement periods, the computer is removed from the browse list.
Note There might be up to a 36-minute delay between the time a server goes down and the time it is removed from the browse list.