There's a distinction here between DNS hosting (telling people what address "foo.com" should point to) and domain registration (making it known that your server

There's a distinction here between DNS hosting (telling people what address "foo.com" should point to) and domain registration (making it known that your server "owns" that domain and is where people should look for information about it). The former is just running a DNS server, anyone can do it. But the latter involves being an official "registrar" and paying alot of money to add names to the root nameservers' lists.