I was editing my DNS records through my hosting service (nearlyfreespeech) and I got to wondering, how does the international DNS network know that the person who's editing the DNS records is actually me? Why can't some random person go and edit the records?
Presumably, your registrar where you registered your domain name and likely where you modify your DNS records is known as the authority for your domain with a SOA statement of authority record. All registrars are a bit different, but assuming that you do not share your username and password with anyone, only you and your registrar can actually change the records.
There is no one DNS. Your DNS is just a few of a huge network of referring DNS servers throughout the world. When you register your domain name, the gTLD or ccTLD DNS server will have a DNS server listed to resolve the domain name so that when someone wants to look-up your domain name, it starts at the top (if you will) and queries the TLD DNS for where to find the records for your domain. Okay. This is a bit of an over simplification, but I thought getting more technical would make a long and boring answer.