NameVirtualHost 1.2.3.4:80

<VirtualHost 1.2.3.4:80>
        DocumentRoot /home/www1
        ServerName domain.com
        ServerAlias *.domain.com
</VirtualHost>

<VirtualHost 1.2.3.4:80>
        DocumentRoot /home/www2
        ServerName preview.domain.com
</VirtualHost>