The Council of European National Top Level Domain Registries, has produced the following video to help explain the functioning of the Domain Name System (DNS). (via.)
It is nicely done and very colourful. I particularly liked how they producers show how fast DNS resolution is with the lump of sugar falling into the cup of coffee.
Several years ago the very popular TV show Die Sendung mit der Maus did a perhaps better job explaining the DNS (to young children). Even if you don't understand German, it is very worthwhile seeing -- if only to see the old-tech :-)
What you should really do, however, is to buy my book Alternative DNS Servers -- you'll then fully grasp what the DNS is all about.