TCP/IP can be configured to search the local host table file, HOSTS,
for mappings of remote host names to IP addresses. The HOSTS file
format is the same as the format for host tables in the version
4.3 Berkeley Software Distribution (BSD) UNIX /etc/hosts
file. For example, the entry for a computer with an address of 22.214.171.124
and a host name of trey.research.com looks similar to this:
the sample HOSTS file that is created when you install TCP/IP to
include remote host names and their IP addresses for each computer
with which you will communicate. This sample file also explains
the syntax of the HOSTS file.
names are used in virtually all TCP/IP environments. A host name
always corresponds to an IP address that is stored in a HOSTS file
or on a DNS server and is assigned by an administrator to identify
a TCP/IP host or default gateway. A host name can be used in place
of an IP address when using ping or other TCP/IP utilities.
names are not used in the Windows 98 network user interface,
such as Network Neighborhood or Net.exe. The only time a host name
is used to access a Windows-based computer is when ping or
ftp or another TCP/IP utility is used. In this case, the
host name and corresponding IP address must be stored in a HOSTS
HOSTS file is a static file used to map host names to IP addresses.
This file provides compatibility with the UNIX HOSTS file. The following
describes HOSTS file entries:
- A single entry consists of
an IP address corresponding to one or more host names.
- Entries are case-sensitive.
Therefore, it is a good idea to assign multiple host names with
example, to connect to the UNIX host archive.research.com at the
IP address 126.96.36.199, make two entries in the HOSTS file:
way, a user can connect to ARCHIVE using a utility, whether or not
the CAPS LOCK is enabled.
HOSTS file must reside on each system. By default, the host name
localhost is an entry in the HOSTS file with the loopback
HOSTS file is parsed whenever a host name is referenced. Names are
read in a linear fashion. The most commonly used names should be
near the beginning of the file. HOSTS file entries do not replace
or interact with Windows-based NetBIOS computer names in any way.
following shows the default HOSTS file provided with Windows 98.
# Copyright (c) 1994 Microsoft Corp.
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows 98
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# Additionally, comments (such as these) may be inserted on individual
# lines or following the computer name denoted by a '#' symbol.
# For example:
# 188.8.131.52 rhino.acme.com # source server
# 184.108.40.206 x.acme.com # x client host
you use Microsoft TCP/IP on a local network with any combination
of computers running Windows 98, Windows NT, LAN Manager,
or Windows for Workgroups, server names are automatically mapped
to their corresponding IP addresses. However, to map server names
across remote networks connected by routers (or gateways), you can
use the LMHOSTS file if WINS servers are not available on the network.
The LMHOSTS file is commonly used to locate remote computers for
Microsoft networking file, printer, and remote access services,
and for domain services, such as logon, browsing, replication, and
LMHOSTS file used by Windows 98 contains mappings of IP addresses
to Microsoft networking computer names (which are NetBIOS names).
Microsoft LAN Manager 2.x TCP/IP LMHOSTS files are compatible
with Microsoft TCP/IP.
TCP/IP loads the LMHOSTS file into memory when the computer is started.
The LMHOSTS file is a text file in the \Windows directory that lists
the IP addresses and computer names of remote Windows networking
servers that you want to communicate with. The LMHOSTS file should
list all the names and IP addresses of the servers you regularly
example, the LMHOSTS table file entry for a computer with an address
of 220.127.116.11 and a NetBIOS computer name of Finance1 looks like
format for the LMHOSTS file is the same as the format for host tables
in 4.2 MSD UNIX systems, with the exception that LMHOSTS does not
allow a scoped name to be indicated. The computer name is optionally
enclosed in quotation marks (this is necessary for computer names
that contain spaces).
To create an LMHOSTS file
Use a text editor to create a file named LMHOSTS, or edit
the default file named Lmhosts.sam in the \Windows directory and
then save this file as LMHOSTS. This LMHOSTS file will be checked
by default as the machine starts.
In the LMHOSTS file, type the IP address and the host name
of each computer that you want to communicate with. Separate the
items with at least one space.
in the LMHOSTS file are not case-sensitive.
will want to use LMHOSTS for smaller networks or to find hosts on
remote networks that are not part of the WINS database (because
name query requests are not broadcast beyond the local subnetwork).
If WINS servers are in place on an internetwork, users do not have
to rely on broadcast queries for name resolution, because WINS is
the preferred method for name resolution. Therefore, with WINS servers
in place, LMHOSTS may not be necessary.
the LMHOSTS file is read when WINS or broadcast name resolution
fails, and resolved entries are stored in a system cache for later
access. When the computer uses the replicator service and does not
use WINS, LMHOSTS entries are required on import and export servers
for any computers on different subnetworks participating in the
You can use Notepad or any other text editor to edit the sample
Lmhosts.sam file that is automatically installed in the \Windows
directory. The following rules apply for entries in LMHOSTS:
- Each entry should be placed
on a separate line.
- The IP address should begin
in the first column, followed by the corresponding computer name.
- The address and the computer
name should be separated by at least one space or tab.
- The # character is usually
used to mark the start of a comment. However, it can also designate
special keywords, as described in this section.
keywords listed in the following table can be used in LMHOSTS using
Microsoft TCP/IP. Notice, however, that LAN Manager 2.x treats
these keywords as comments.
Added after an entry to cause that entry to be preloaded
into the name cache. #PRE entries in LMHOSTS are looked up
and cached prior to WINS lookup. #PRE must be appended for
entries that also appear in #INCLUDE statements; otherwise,
the entry in #INCLUDE is ignored.
Added after an entry to associate that entry with the domain
specified by domain. This keyword affects how the Browser
and Logon services behave in routed TCP/IP environments. To
preload a #DOM entry, you must also add the #PRE keyword to
Forces the system to seek the specified filename
and parse it as if it were local. Specifying a universal naming
convention (UNC) filename allows you to use a centralized
LMHOSTS file on a server. You must map the server before its
entry in the #INCLUDE section, and also append #PRE to ensure
that it is preloaded (otherwise, the #INCLUDE will be ignored).
Used to group multiple #INCLUDE statements. Any single
successful #INCLUDE statement causes the group to succeed.
Used to mark the end of an #INCLUDE grouping.
Support for nonprinting characters in NetBIOS names. Enclose
the NetBIOS name in quotation marks and use \0xnn hexadecimal
notation to specify a hexadecimal value for the character.
This allows custom applications that use special names to
function properly in routed topologies. However, LAN Manager
TCP/IP does not recognize the hexadecimal format, so you surrender
backward compatibility if you use this feature.
that the hexadecimal notation applies only to one character
in the name. The name should be padded with blanks so the
special character is last in the string (character 16).
following example shows how all of these keywords are used:
18.104.22.168 localsrv #PRE
22.214.171.124 trey #PRE #DOM:networking #net group's PDC
126.96.36.199 "appname \0x14" #special app server
188.8.131.52 popular #PRE #source server
#INCLUDE \\localsrv\public\lmhosts #adds LMHOSTS from this server
#INCLUDE \\trey\public\lmhosts #adds LMHOSTS from this server
In the preceding example:
- The servers named localsrv
and trey are preloaded so they can be used later in an
#INCLUDE statement in a centrally maintained LMHOSTS file.
- The server named "appname
\0x14" contains a special character after the 15 characters
in its name (including blanks), so its name is enclosed in quotation
- The server named popular
is preloaded, based on the #PRE keyword.
IP Address PDCName #PRE #DOM:domainname
IP Address "domainname,,,,,\0x1b" #PRE
Where IP Address is the address of your PDC.
PDCName is the name of your PDC
domainname is the name of your Domain
domainname,,,,, is also the name of your Domain. However, the
commas represent spaces, and in this line, your domainname
must be 15 characters. If it isn't, pad it with the appropriate
number of spaces to reach 15 characters.
And...use the quotes
Your PDC acts as the Domain Master Browser, and as such, should
have the browse lists of all Segment Master Browsers (if you have
a multi-segment network), thus a list of all network devices.
The above LMHosts file tells your PC the name of the logon domain
controller (your PDC), and the second line says use the PDC as
your browse master.
If you can ping your PDC and net use a share to the PDC, then
the above should work.
Guidelines for LMHOSTS
you use a host table file, be sure to keep it up to date and
organized. Follow these guidelines:
the LMHOSTS file whenever a computer is changed or removed
from the network.
#PRE statements to preload popular entries into the local
computerís name cache and to preload servers that are included
with #INCLUDE statements.
- Because LMHOSTS files are searched one line at a time
from the beginning, you can increase the speed of searches
for the entries used most often by placing frequently used
servers near the top of the file. Follow these with less
frequently used servers, and then remote #INCLUDE statements.
The #PRE entries should be at the end of the file, because
these are preloaded into the cache at system startup time
and are not accessed later. Comment lines add to the parsing
time, because each line is processed individually.