The organization of this book derives from Cisco's published exam objectives, and each topic is addressed in a similar way. A given topic area typically opens with a discussion of what it's good for and why you would want to configure it. Then, you get to see how the subject looks in action--for a protocol, you'll see the sequence of messages that go back and forth. From there, it's on to the specifics of how Cisco equipment implements the technology. You'll find configuration file listings that illustrate variations on the theme and Internetwork Operating System (IOS) command sequences. Review questions, which are followed by their answers--plus comments--appear at the end of each chapter. --David Wall