Mine

eCanonicalName off
ServerAlias *.ddsystems.com
ServerName *.ddsystems.net
RewriteEngine On
# Skip www.ddsystems.net
RewriteCond %{HTTP_HOST} !^www\.
RewriteCond %{HTTP_HOST} ^([^.]+)\.ddsystems\.net
RewriteRule ^/(.*)$  /var/www/vhosts/%1/$1/httpdocs [L]i
DocumentRoot /var/www/vhosts/$1/httpdocs