Actually, this isn't just if you don't setup DNS records for your domain name. If you configure some subdomains with name.com, then all other subdomains for that domain go to a parked page.

For example, my wife's website is jesleephotos.com. The subdomains store and www (along with some others that I don't wish to advertise :) go to the correct destination. The subdomain stuff, x, random, mail, etc all go to parked domain.

I might end up adding an A record for *.jesleephotos.com as a catchall and point it to some IP address I can get that will forward everything to www.