Apache default VirtualHost

I found the answer: I remembered that Apache uses the first block if no other matching block is found, so I've added a block without a serveralias at the top of the blocks:

NameVirtualHost *

<VirtualHost *>
    DocumentRoot /defaultdir/
</VirtualHost>

<VirtualHost *>
    ServerAdmin [email protected]
    DocumentRoot /someOtherDir/
    ServerAlias ip.of.the.server
</VirtualHost>

<VirtualHost *>
    ServerAdmin [email protected]
    DocumentRoot /someroot/
    ServerAlias example.com *.example.com
</VirtualHost>

If you are using Debian style virtual host configuration (sites-available/sites-enabled), one way to set a Default VirtualHost is to include the specific configuration file first in httpd.conf or apache.conf (or what ever is your main configuration file).

# To set default VirtualHost, include it before anything else.
IncludeOptional sites-enabled/my.example.com.conf

# Load config files in the "/etc/httpd/conf.d" directory, if any.
IncludeOptional conf.d/*.conf

# Load virtual host config files from "/etc/httpd/sites-enabled/".
IncludeOptional sites-enabled/*.conf