Sometimes may forget that this is an exam preparation aid, but realistic problems and multiple choice review questions bring readers back to the task at hand. complex solution to the problem and quick answers to review questions appear on the back of this book (along with the glossary, both large), but the answer key would be more useful if incorporated a brief discussion explaining the reasoning behind the correct answer. - David Wall Topics covered: All elements forbidden from CCDA exam (640-441), including the Open Systems Interconnect (OSI) reference model, Ethernet, network topology, network protocols, routing, bridging, switching, and the basics of Cisco hardware and tool products software.