VirtualHost Examples: Name-based hosts on more than one IP address

This document attempts to answer the commonly-asked questions about setting up virtual hosts.
These scenarios are those involving multiple web sites running on a single server, via name-based or IP-based virtual hosts.

Note: Any of the techniques discussed here can be extended to any number of IP addresses.
The server has two IP addresses. On one (172.20.30.40), we will serve the "main" server, server.domain.com and on the other (172.20.30.50), we will serve two or more virtual hosts.############################################################################
Server configuration
Listen 80

# This is the "main" server running on 172.20.30.40
ServerName server.domain.com
DocumentRoot /www/mainserver

# This is the other address
NameVirtualHost 172.20.30.50

<VirtualHost 172.20.30.50>
DocumentRoot /www/example1
ServerName http://www.example1.com/
# Other directives here ...
</VirtualHost>

<VirtualHost 172.20.30.50>
DocumentRoot /www/example2
ServerName http://www.example2.org/
# Other directives here ...
</VirtualHost>
###############################################################################
Any request to an address other than 172.20.30.50 will be served from the main server. A request to 172.20.30.50 with an unknown hostname, or no Host: header, will be served from http://www.example1.com/