I bought this book about a month ago. I read the book about two times from cover to cover, highlighting the important parts. Also bought the Exam Cram book, as a review and passed the exam today with a 800/900 the first time. The author Groth really breaks the the subject, also the CD was great. A word to the wise, pay close att. to the IP subnetting part. Also the IPv4 and IPv6. thanks Sybex!