These settings are applicable to Redhat/ Fedora / CentOS and I am not aware if this holds good even on other Distros.

Important File / Folder Locations

• Location of HTTPD (Apache) Configuration File:
  /etc/httpd/conf/httpd.conf
• Location of PHP Configuration File (php.ini):
  /etc/php.ini

Service Related Information

Enabling / Disabling Services
The chkconfig command can be used for enabling / disabling services on Redhat based linux distributions.

EX: # chkconfig httpd –add
EX: # chkconfig httpd on
EX: # chkconfig –list httpd
EX: # chkconfig httpd of
EX: # chkconfig httpd –del

Starting / stopping / a service

service <service name> start/stop
EX: # service httpd stop
EX: # service httpd start

I would give these examples considering you wish to have

www.url-1.com and www.url-2.com.

Step 1: Add your new domain to hosts file.

This is very essential else you will get address not found error!

Host file is usually located in /etc/hosts

Double click on the "hosts" file, and it should open in "gedit".
The configuration should resemble something like this:

#if you would like to setup only for local system

127.0.0.1 url1.com www.url1.com url2.com www.url2.com

#setting up for a IP which can be accessessible outside

192.168.1.1 url1.com www.url1.com url2.com www.url2.com

Step 2: Load VHOST Module in Apache

Now open the Apache configuration file "httpd.conf" and make sure that vhost alias module is loaded as shown.

Usual FILE LOCATION: etc/httpd/conf/httpd.conf

LoadModule vhost_alias_module modules/mod_vhost_alias.so

Step 3: Add Virtual Host Entries
Now it is time to make proceed and configure Apache Server (the httpd service) to serve files for the different websites.

NameVirtualHost 127.0.0.1:80

</VirtualHost 127.0.0.1:80>
      ServerName www.url-1.com
      DocumentRoot /var/www/url1-folder
</virtualhost>
</VirtualHost 127.0.0.1:80>
      ServerName www.url-2.com
      DocumentRoot /var/www/url2-folder
</VirtualHost>

OR

NameVirtualHost 192.168.1.7:80

</VirtualHost 192.168.1.7:80>
      ServerName www.url-1.com
      DocumentRoot /var/www/url1-folder
</VirtualHost>

<VirtualHost 192.168.1.7:80>
      ServerName www.url-2.com
      DocumentRoot /var/www/url2-folder
</VirtualHost>

NOTE: The following settings usually do not work on Linux platform:

<VirtualHost *:80> or NameVirtualHost *.80

Instead you need to use the actual IP address such as:

<VirtualHost 192.168.1.7:80> or NameVirtualHost 192.168.1.7.80

If you use *.80, you may always see the default website for both url-1.com and url-2.com.

You may find more virtualhost examples at the following URL: http://httpd.apache.org/docs/2.2/vhosts/examples.html

For CentOS There are a few strict rules to follow as given in:
http://www.centos.org/docs/5/html/Deployment_Guide-en-US/s1-apache-virtualhosts.html

Setup 4: The final Step – Restart Apache
      The final step is to re-start httpd service using the following command.

service httpd restart

Now you should be able to browse www.url-1.com and www.url-2.com using any web-browser such as Mozilla firefox.