Don't get this book if you want to learn networks from the ground up - it's not very well composed, meandering, and has very little diagrams to back up the pages of text. You'd be far better of buying something like a Ciscopress title, or one of the many Sybex/McGrawHill/Coriolis books on basic internetworking.
I'm now a network consultant, but bought this book a few years back when I was moving in from a different technical area - I read the majority of the book, but none of it gelled or furthered my understanding too well. Reading it now, I can see why - it suffers from lack of direction, and misses out whole areas that are real fundamentals. IP addressing gets a page, whereas things like modulation techniques get reams.
All in all, it suffers from going waay too in depth in certain areas, yet skips over sections that the majority of people will want to read, and lacks in diagrams to explain things visually.
Ian.