Using Wildcard on Domain Setting, A Name or Cname

Tweet

I currently setup my domain server and not sure about one thing that I hope all of you can help me. Till this time I do not face any problem with my setting and using CNAME entry pointer to Google Apps. Six days ago, I signed up for a service that provide me to change CNAME and must be using wildcard on it. Are wildcard CNAME not causing any side effects for common DNS setting? How about old CNAME entries that redirect to some services like Google Apps? Is there any alternative choice how to setup DNS: A record and CNAME properly or could be setup without using wildcard? For information, the service I told before is an openID system. If we want to setup OpenID for members so they can use it from their subdomain, this domain must using wildcard in CNAME entry and it's subdomain will automatically become an OpenID for the member. Thank you very much for any suggestion and help.