host name resolution

Host Name Resolution is the process by which a host determines the IP address of another host given its host name or fully qualified domain name (FQDN) on a TCP/IP network.

What is Host Name Resolution?

The process by which a host determines the IP address of another host given its host name or fully qualified domain name (FQDN) on a TCP/IP network.

How it works

Suppose you go to the command prompt of a machine running 32-bit Microsoft Windows NT and type ping followed by a host name or FQDN of another host on the network. The host name or FQDN of the target host must first be resolved into its IP address before the TCP/IP utility ping can occur. This process is called host name resolution.

A number of different methods can be used to perform host name resolution. The following table shows the order in which these are attempted on a Microsoft network.

The methods are tried in succession until the host name is resolved into its IP address or until name resolution finally fails. Some methods will not be available - for example, if there is no DNS server or NetBIOS Name Server (NBNS) on the network.

Host Name Resolution Methods in the Order Applied

Host Name Resolution Methods Comments
Check whether the target host is the local host.
The local host knows its own host name!
Check local hosts file.
This check is performed only if a hosts file has been configured.
Contact DNS server.
This check is performed only if the DNS tab of the TCP/IP property sheet has a DNS server specified on it. The local host tries again at intervals of 5, 10, 20, 40, 5, 10, and 20 seconds.
Check local NetBIOS name cache. (Unique to Microsoft networks.)
The cache contains recently resolved NetBIOS names. (On Microsoft networks, NetBIOS names and host names are usually the same.)
Contact NBNS. (Unique to Microsoft networks.)
This check is performed if NBNS has been configured by creating a Windows Internet Name Service (WINS) record within the DNS database. On a Microsoft network, this is usually a WINS server. The local host tries three times to contact the WINS server and then tries secondary WINS server three times if configured.
Perform local broadcast. (Unique to Microsoft networks.)
Local host broadcasts a NetBIOS name query request packet three times.
Check local lmhosts file. (Unique to Microsoft networks.)
This check is performed if an lmhosts file has been configured.

If all methods fail, an error message states that the computer could not be found on the network.

NOTE

There is a separate series of steps for attempting to resolve NetBIOS names on a network that uses WINS. For more information, see the entry on NetBIOS name resolution elsewhere in this work.