Internetworking must be built around the business at hand in order to provide easy access to pertinent information regardless of location, time, or system. Much of the information included in this book is based on questions I have received in class. I have to send out a special thanks to all of my students and coworkers from TCP/IP to CCNA to CCNP and others over the years who have kept me on my toes. I wouldn't want to forget my technical reviewers, who have helped me make this book what it is today. Thank you Scott Morris, Rick Burts, Marty Adkins, Mark Olivo, and Chris Heffner. I would also like to thank Charlie Mann for testing the hands-on scenarios and Trouble Tickets.