I purchased this book as a suppliment to my Cisco ICRC and ACRC class materials. As I began to read this book, the errors were easy to find. Stay with the course materials from the classes. The book makes to many errors to rely upon as a study guide for the exam. As I took the Cisco ACRC class, I was able to find way to many mistakes in this book. Unlike Mr. Know-it-all from LA, I don't claim to know it all, as nobody does. But you don't have to be a genious to see the errors in this one.