Configuring Windows NT with TCP/IP requires the IP address and computer name, which are unique identifiers for the computer on the network. The IP address, as described earlier in this chapter, is the unique address by which all other TCP/IP devices on the internetwork recognize that computer. For TCP/IP and the Internet, the computer name is the globally known system name plus a DNS domain name. (On the local network, the computer name is the NetBIOS name that was defined during Windows NT Setup.)
Computers use IP addresses to identify each other, but users usually find it easier to work with computer names. A mechanism must be available on a TCP/IP network to resolve computer names to IP addresses. To ensure that both computer name and address are unique, the Windows NT computer using TCP/IP registers its name and IP address on the network during system startup. A Windows NT computer can use one or more of the following methods to ensure accurate name resolution in TCP/IP internetworks:
Windows NT computers can use WINS if one or more WINS servers are available that contain a dynamic database mapping computer names to IP addresses. WINS can be used in conjunction with broadcast name resolution for an internetwork where other name resolution methods are inadequate. As described in the following section, WINS is a NetBIOS over TCP/IP (NBT) mode of operation defined in RFC 1001/1002 as p-node.
Windows NT computers can also use broadcast name resolution, which is a NetBIOS over TCP/IP mode of operation defined in RFC 1001/1002 as b-node. This method relies on a computer making IP-level broadcasts to register its name by announcing it on the network. Each computer in the broadcast area is responsible for challenging attempts to register a duplicate name and for responding to name queries for its registered name.
The Domain Name System (DNS) provides a way to look up name mappings when connecting a computer to foreign hosts using NetBIOS over TCP/IP or Windows Sockets applications, such as FTP. DNS is a distributed database designed to relieve the traffic problems that arose with the exploding growth of the Internet in the early 1980s.
On a local computer, the HOSTS file (used by Windows Sockets applications to find TCP/IP host names) and LMHOSTS file (used by NetBIOS over TCP/IP to find Microsoft networking computer names) can be used to list known IP addresses mapped with corresponding computer names. The LMHOSTS file is still used for name resolution in Windows NT for small-scale networks or remote subnets where WINS is not available.
This section provides details about name resolution in Windows NT after first presenting some background information about the modes of NetBIOS over TCP/IP that can be used in Microsoft networks.