The Windows Internet Name Service (WINS) is Microsoft's implementation of a NetBIOS name server (NBNS). As such, WINS inherits much of NetBIOS's characteristics. First, WINS is flat; you can only have machines named
fred or workgroups like CANADA or USA. In addition, WINS is dynamic: when a client first comes online, it is required to report its hostname, its address, and its workgroup to the local WINS server. This WINS server will retain the information so long as the client periodically refreshes its WINS registration, which indicates that it's still connected to the network. Note that WINS servers are not domain or workgroup specific; they can appear anywhere and serve anyone.
Multiple WINS servers can be set to synchronize with each other after a specified amount of time. This allows entries for machines that come online and offline on the network to propagate from one WINS server to another. While in theory this seems efficient, it can quickly become cumbersome if there are several WINS servers covering a network. Because WINS services can cross multiple subnets (you'll either hardcode the address of a WINS server in each of your clients or obtain it via DHCP), it is often more efficient to have each Windows client, no matter how many Windows domains there are, point themselves to the same WINS server. That way, there will only be one authoritative WINS server with the correct information, instead of several WINS servers continually struggling to synchronize themselves with the most recent changes.
The currently active WINS server is known as the
primary WINS server. You can also install a secondary WINS server, which will take over in the event that the primary WINS server fails or becomes inaccessible. Note that there is no election to determine which machine becomes a primary or backup WINS server - the choice of WINS servers is static and must be predetermined by the system administrator. Both the primary and any backup WINS servers will synchronize their address databases on a periodic basis.
In the Windows family of operating systems, only an NT Workstation or an NT server can serve as a
WINS server. Samba can also function as a primary WINS server, but not a secondary WINS server.
