While the explanation of solid and often intimidating, once you get through this book, you'll be ready to face - and pass - the CCNA exam dangerous!. Todd Lammle assumes that the reader has a passing familiarity with basic networking concepts, and he launched straight into an in-depth review of the OSI network model without mentioning what hubs, routers, and switches. He then worked your way to explain TCP / IP and TCP / IP subnetting, well-known concept confusing for beginners, and the truth, while middle-level technicians may be confused here as well. Unlike many other CCNA study guide, which briefly touched on subnetting and then provide a list of common subnet mask for rote memorization, Lammle really want you to understand why a particular mask and work address ranges. The explanations here are real migraine-inducer, but it was more the fault of the TCP / IP 's inherent complexity of the explanation Lammle's. Lammle himself admitted that he expects his audience should reread the TCP / IP section at least once - but if you take the time to bear down, do the math, and really learn, you do not need to read another chapter on TCP / IP subnetting again. The next part of the deal with Cisco routing order book, and here that the CCNA Study Guide really shines. Cisco router command evil to provide the user with a flood of information, and plug it in. network statistics often send young trainees CCNA to info-shock. While the details are presented in the chapters WAN solid, they seem a bit out of proportion: while Wide Area Networks, and in particular, ISDN, a sizable part of the CCNA exam, the ISDN here is all of 20 pages. It's not that there is not enough to pass, but Lammle did not provide details of common wealth in the last chapter. Like any good certification book, there is a quiz to test your skills, and you will not lack for choice here - seven "open answer" questions, 20 multiple choice questions, and hands-on workshops grace the end of each chapter. The question is quite hard, and is a good test of your understanding as a whole, but you probably can expect to find harder questions on the actual exam. Rounding of this book is productive hands-on walk-through configuration of the Catalyst 1900 Switch, a complete list of CCNA router commands, and a glossary of terms, page 70.