Types
of Names
There are two types of user-friendly names: host names and NetBIOS
names.
Host
Names
A
host name is a user-friendly name that is assigned to a computer’s
IP address to identify it as a TCP/IP host. The host name can be up
to 255 characters in length and can contain alphabetic and numeric
characters, hyphens, and periods.
Host
names can take various forms. The two most common forms are alias
and domain name. An alias is a single name associated with an IP
address, such as London. A domain name is structured for use on the
Internet and includes periods as separators. An example of a domain
name is london.nwtraders.msft.
NetBIOS
Names
A
NetBIOS name is a 16-character name that is used to identify a
NetBIOS resource on the network. A NetBIOS name can represent a
single computer or a group of computers, but only the first 15 of
the characters may be used for the name. The final character is used
to identify the resource or service that is being referred to on the
computer. An example of a NetBIOS resource is the File and Printer
Sharing for Microsoft Networks component on a computer running
Windows 2003. When your computer starts, this component registers a
unique NetBIOS name, based on the name of your computer and one
character identifier that represents the
component.
In
Windows 2003, the NetBIOS name uses up to the first 15 characters of
the host name and cannot be configured separately. Although Windows
2003 does not require NetBIOS names, previous versions of
Windows require NetBIOS names to support networking capabilities.
Static
IP Mapping
When
users specify a user-friendly name to communicate with a destination
computer, TCP/IP still requires an IP address for transmission to
occur, so the computer name is mapped to an IP address. This mapping
is then stored in either a static or dynamic table. In a static
table, mappings are stored in one of two text files: the Hosts file
or the Lmhosts file.
The
advantage of using a static table is that, because it is a text file
located on each computer, it is customizable. Each user can create
any number of required entries, including easy-to-remember aliases
for frequently accessed resources. However, it is difficult to
maintain and update static tables if the tables contain
a
large number of IP address mappings or if the IP addresses change
often.
Hosts
File
The
Hosts file is a text file that contains IP address-to-host name
mappings.
Within the Hosts file:
-
Multiple host names can be assigned to the same IP address. A
server at the IP address 167.91.45.121 can be referred to by its
domain name (london.nwtraders.msft) or by an alias (London).
This allows a user at this computer to refer to this server by
using the alias London rather than by typing the entire domain
name.
-
Entries are case-sensitive, depending upon the platform. Hosts
file entries for computers running Windows 2003 and Microsoft
Windows NT®
version 4.0 are not case-sensitive.
Lmhosts
File
The
Lmhosts file is a text file that contains the IP address-to-NetBIOS
name mappings. A portion of the Lmhosts file is pre-loaded into
memory and is referred to as the NetBIOS name cache.
