|postcard from DNS|
Last week a mate asked about DNS, and this is what I sent him ..
Humans use names for things on the Internet, but computers use numbers, so there's a long established system for converting between the 2. It's called DNS (stands for Domain Name Service), and it's a database distributed amongst hundreds of computers on the internet, all of which talk to each other and keep themselves up to date. In our case DNS will convert "www.cyclevision.com.au" into 126.96.36.199 which the routing system understands and knows how to use. And you get to see the Cyclevision web site.
The Domain Name bit of DNS is "www.cyclevision.com.au", and there are companies that are able to register domain names on request - and on receipt of an amount of money. Normally the amount is small, and needs to be paid annually. In return for the money you get your domain name and the registrar will create entries in their bit of the global DNS system to make sure that the name get converted into the right set of numbers.
The right set of numbers is determined by the company that hosts your web site - change the hosting company and the numbers have to change, but there's a process for doing this which isn't usually too arduous.
Different bits of the domain name actually do mean something. In our case:
There's a lot more that happens "behind the scenes", but for the most part you can safely ignore it.
You could perhaps liken the whole thing to the mobile phone network, a bit. When you call someone the network needs to know where the phone you're calling is, and it uses it's own database for that. Just like DNS. If the phone you want to call doesn't have an entry in the database you can't talk to it.