Some ideas
Don't let them select a name. - Create a random url ghrff.domain.com
Don't do this on your primary domain buy a new one
If you still want to go ahead and you've created an 'a' record for www or mail previously your a record will superseed the wildcat entry which will create a bug where the user cannot access their subdomain. You need to filter any a records you've created to avoid this.
Don't do this on your primary domain buy a new one
If you still want to go ahead and you've created an 'a' record for www or mail previously your a record will superseed the wildcat entry which will create a bug where the user cannot access their subdomain. You need to filter any a records you've created to avoid this.