As i said in the title, I purchased this book with the hope of find, at least, the same good material of the CCDA Certification Guide (I'm CCDA, of course because of this book among others), but, sadly, what i'd find with this book, was a very big amount of pages that makes the most confusing explanation that was possible, with a very big amount of open questions that the real answer to those was the Odom's thinking finally, instead of making questions more precise, like the questions of the exam. I apologize to purchase this book.