Don't make the same mistake I made! If you rely on this book to pass the BCMSN exam then you will need a miracle! The book has lots of technical errors to do with concepts associated with the BCMSN. I stopped reading it after the first two chapters. The title of the book is incorrect to start with. It should read "Building Cisco Multilayer Switched Networks" not "Building Cisco Multilayer Switching Networks" ! Some/all of the writers (and reviewers) just missed too many important concepts; and the figures are not illustrative of the concepts being discussed at all ! And the companion CD questions are not indicative of what's in the exam at all ! How do I know all this ? Because I passed the BCMSN thanks mostly to the Cisco Press book (by Karen Webb)