Configure HOSTS Files

Select Certification Bootcamp :
MCSE MCSE+Security CCNA CCNP RHCE Register Course Fees Home

Leading MCSE, CCNA, CCNP Certification boot camp training provider in India, USA, UK.

Configure HOSTS Files

The HOSTS file is an ASCII text file that statically maps local and remote host names and IP addresses. It is located in \systemroot\ System32\Drivers\etc.

The HOSTS file is not case sensitive, however, some utilities that you will use may be. Entries in the HOSTS file are limited to 255 characters per entry. The HOSTS file is used by PING and other Winsock utilities to resolve host names locally and remotely. One HOSTS file must reside on each host, and the file is read from top to bottom. As soon as a match is found for a host name, the file stops being read. For that reason, when there are duplicate entries, the latter ones are always ignored, and the most commonly used names should be near the top of the file.

The following is an example of the default HOSTS file:

# Copyright (c) 1993-1995 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows NT.
#
# 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 space.
#
# Additionally, comments (such as these) may be inserted on individual lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host

127.0.0.1 localhost

You should notice several things in this file. First, the pound sign (#) indicates a comment. When the system reads the file, every line beginning with a comment is ignored. When a # appears in the middle of a line, the line is read only up to the sign. If this file were in use on a live system, you would delete the first 17 lines or move them to the end of the file to keep them from being read every time the file is referenced.

The second thing to note is the entry:

127.0.0.1 localhost

This is a loopback address in every host. It references the internal card, regardless of the host address, and can be used for diagnostics to verify that connections are working properly internally, before testing that they are working properly down the wire.

Within the HOSTS file, fields are separated by white space that can be tabs or spaces. As mentioned earlier, a host can be referred to by more than one name—to do so, separate the entries on the same line with white space, as shown in the following example:

127.0.0.1 me loopback localhost
199.9.200.7 SALES7 victor
199.9.200.4 SALES4 nikki
199.9.200.3 SALES3 cole
199.9.200.2 SALES2 victoria
199.9.200.1 SALES1 nicholas
199.9.200.5 SALES5 jack
199.9.200.11 ACCT1
199.9.200.12 ACCT2
199.9.200.13 ACCT3
199.9.200.14 ACCT4
199.9.200.15 ACCT5
199.9.200.17 ACCT7

The aliases are other names by which the system can be referred. Here, “me” and “loopback” do the same as “localhost,” and “nicholas” is the same as “SALES1.” If an alias is used more than once, the search stops at the first match because the file is searched sequentially.

Exercise 11.2 allows you to practice editing this file.

Vibrant Advantage :

No Prestudy
Longest Duration Camp
Chalk Talk Training
Highest Passing Rate
Bootcamp since 1999
Guaranteed Certification ...

Testimonials :

MCSE Certification boot camp

The instructor taught real world experience and did not just teach us to pass the test. He knew the subject well and was encouraging. His lectures were very well delivered....

Colver Dennis, USA