There is 2 places that need to be set up in order to use wildcard DNS.
1) You must set up * in your DNS zone. This can be done either from the registrar that you registered your domain with or on the server itself that has the DNS set up. (Like ns1.yourdomain.com)
* IN A xxx.xxx.xxx.xx <-- Your IP address of web server (also, put this at the end of your dns file so that it will process other subdomains first before processing this statement).
THEN
2) You have to edit your httpd.conf file and include a wildcard alias for your domains.
ServerName
www.hl2x.com
ServerAlias *.hl2x.com hl2x.com
^^ You have to include a *.yourdomain.com so that apache will know that anything.yourdomain.com will go to your document root.