What is the logic behind VirtualHost / NameVirtualHost

I understand the concepts of name-based virtual hosts (i.e. serving two domain names differently) and ip-based virtual hosts (i.e. a serving two ip's differently)

But...

Should I always specify an IP address, or is it OK to use *? Many examples of name-based virutal hosting still specify IP addresses. Why is VirtualHost a block and NameVirtualHost a directive? Why do I need NameVirtualHost for IP-based virtual hosts?

Solution 1:

Should I always specify an IP address, or is it OK to use *?

You can specify * in both directives.

NameVirtualHost *    
<VirtualHost *> ...

Why is VirtualHost a block and NameVirtualHost a directive?

NameVirtualHost only defines IP on which you'll use name virtual hosts. Doesn't contain other directives, so no reason why it should be block. On the other hand VirtualHost does contain other directives for particular virtual host, so it has to be a block.

Why do I need NameVirtualHost for IP-based virtual hosts?

You don't need it. See example.

Recommended reading: Apache Virtual Host documentation