H-Node is a NetBIOS name resolution method used for name registration and resolution.
What is H-Node?
A NetBIOS name resolution method used for name registration and resolution. H-node is one of the types of NetBIOS over TCP/IP nodes defined in Request for Comments (RFC) numbers 1001 and 1002, and is supported by computers running Microsoft Windows NT and Windows 2000.

How it works
Name resolution is the process of converting the name of a host on the network into a network address, such as an IP address. Name resolution must be performed to establish communication over a network. H-node is one of four basic methods supported by Windows NT and Windows 2000 for resolving NetBIOS host names (that is, computer names) into IP addresses.
If a computer running Windows NT or Windows 2000 is configured as an H-node machine, it first tries to use a NetBIOS name server to resolve names of other hosts on the network; this is the way a P-node machine functions. A server running Windows NT or Windows 2000 with the Windows Internet Name Service (WINS) configured on it is the typical example of a NetBIOS name server.
If name resolution fails this way (for example, if all WINS servers are down), an H-node machine tries to use broadcasts to resolve the names of the hosts; this is the way a B-node machine functions. H-node is thus a combination of P-node and B-node (in that order), which explains the origin of the term “H-node” because here, “H” stands for “hybrid.”
If there is no WINS server on a network, machines running Windows NT or Windows 2000 automatically configure themselves as B-nodes. If there is at least one WINS server on the network, however, the systems default to H-node.