Users on a Windows NT network often need to know what domains and computers are accessible from their local computer. Viewing all the network resources available is known as browsing. The Windows NT Browser system maintains a list, called the browse list, of all the domains and servers available. For instance, when a user attempts to connect to a network drive using File Manager, the list of servers that is displayed in the Shared Directories box of the Connect Network Drive dialog box is the browse list, and it is provided by a browser in the local computer's domain.
Note For the purposes of this discussion, the term server refers to any computer that can provide resources to the rest of the network. A Windows NT Workstation computer, for instance, is a server in the context of the Browser system if it can share file or print resources with other computers on the network. The computer does not have to be actually sharing resources to be considered a server. In this chapter, specific references to Windows NT Server computers are always made explicitly.
The Windows NT browser system consists of a master browser, backup browsers, and client systems. The master browser maintains the browse list and periodically sends copies to the backup browsers. When a browser client needs information, it obtains the current browse list by remotely sending a NetServerEnum2 application programming interface (API) call to either the master browser or a backup browser. (A NetServerEnum API call is also supported for compatibility with Microsoft LAN Manager networks.)
The centralized browser architecture reduces the number of broadcast datagrams. A datagram is a network packet that is sent to a mailslot on a specified computer (a directed datagram) or to a mailslot on any number of computers (a broadcast datagram). The centralized browser architecture also reduces the demands on the client's CPU and memory.