As the title implies, this is the "Advanced" HOWTO.
While by no means rocket science, some prior knowledge is assumed.
Here are some other references which might help teach you more:
- Rusty Russell's networking-concepts-HOWTO
Very nice introduction, explaining what a network is, and how it is
connected to other networks.
- Linux Networking-HOWTO (Previously the Net-3 HOWTO)
Great stuff, although very verbose. It teaches you a lot of stuff
that's already configured if you are able to connect to the Internet.
Should be located in /usr/doc/HOWTO/NET3-4-HOWTO.txt
but can be also be found