It depends on your DNS provider as to if they support it or not. Often, they will not and you'll simply have to run your own dns nameserver (bind) with a wildca

It depends on your DNS provider as to if they support it or not. Often, they will not and you'll simply have to run your own dns nameserver (bind) with a wildcard config, such as http://community.aegirproject.org/dnswildcard http://community.aegirproject.org/dnswildcard ... Googling around will find you many bind configurations and discussions of this feature.