Creating virtual host configurations on your Apache server does not magically cause DNS entries to be created for those host names. You must have the names in DNS, resolving to your IP address, or nobody else will be able to see your web site. You can put entries in your hosts file for local testing, but that will work only from the machine with those hosts entries.
# Ensure that Apache listens on port 80
Listen 80
# Listen for virtual host requests on all IP addresses
NameVirtualHost *:80
DocumentRoot /www/example1
ServerName www.example1.com
# Other directives here
DocumentRoot /www/example2
ServerName www.example2.org
# Other directives here
The asterisks match all addresses, so the main server serves no requests. Due to the fact that www.example1.com is first in the configuration file, it has the highest priority and can be seen as the default or primary server. That means that if a request is received that does not match one of the specified ServerName directives, it will be served by this first VirtualHost.
You can, if you wish, replace * with the actual IP address of the system. In that case, the argument to VirtualHost must match the argument to NameVirtualHost:
NameVirtualHost 172.20.30.40
# etc ...
However, it is additionally useful to use * on systems where the IP address is not predictable - for example if you have a dynamic IP address with your ISP, and you are using some variety of dynamic DNS solution. Since * matches any IP address, this configuration would work without changes whenever your IP address changes.
The above configuration is what you will want to use in almost all name-based virtual hosting situations. The only thing that this configuration will not work for, in fact, is when you are serving different content based on differing IP addresses or ports.
# Ensure that Apache listens on port 80
Listen 80
# Listen for virtual host requests on all IP addresses
NameVirtualHost *:80
DocumentRoot /www/example1
ServerName www.example1.com
# Other directives here
DocumentRoot /www/example2
ServerName www.example2.org
# Other directives here
The asterisks match all addresses, so the main server serves no requests. Due to the fact that www.example1.com is first in the configuration file, it has the highest priority and can be seen as the default or primary server. That means that if a request is received that does not match one of the specified ServerName directives, it will be served by this first VirtualHost.
You can, if you wish, replace * with the actual IP address of the system. In that case, the argument to VirtualHost must match the argument to NameVirtualHost:
NameVirtualHost 172.20.30.40
# etc ...
However, it is additionally useful to use * on systems where the IP address is not predictable - for example if you have a dynamic IP address with your ISP, and you are using some variety of dynamic DNS solution. Since * matches any IP address, this configuration would work without changes whenever your IP address changes.
The above configuration is what you will want to use in almost all name-based virtual hosting situations. The only thing that this configuration will not work for, in fact, is when you are serving different content based on differing IP addresses or ports.
