The new edition of bestselling Official Cert Guide is available: CCENT\/CCNA ICND1 640-822 Official Cert Guide, Third Edition (ISBN: 978-1-58720-425-8) by Wendell Odom has been updated to refresh the content, add new exercises, and enhance certain topics that are key to understanding for success on the CCENT and CCNA exams. The IP addressing topics have been rewritten and re-organized to mirror proven techniques to learn both the concepts and the specific pieces of the subnetting puzzle. In addition, the TCP\/IP and OSI Networking Models chapter was also completely updated and rewritten.