It's all just a bunch of numbers. The Domain Name System (DMS) is the world's most successful distributed database. With an estimated 200 million domain names in active use (and another 500 million names that have how expired), the size of the database is impressive in itself. But even more impressive is the fact that it's decentralized, existing only in pieces—hundred of thousands of pieces—scattered throughout the world.
The beauty of this underlying architecture is in its ability to keep running forever: there has never been a need to "reboot" the DNS system; it's the ultimate Energizer Bunny.
The software that keeps it all going is BIND, the Berkeley Internet Name Domain package. Configuring, securing, and administering BIND is a straightforward task with few gotchas. Anyone with a basic understanding of IP addresses and the DNS domain name hierarchy can setup a simple DNS/BIND server in a day. And with a little study, a good administrator can maintain an in-house server running multiple domains and sub-domains.