Gary A. Donahue, "Network Warrior: Everything you need to know that wasn't on the CCNA exam" (repost)

Written by networking veteran with 20 years of experience, Network Warrior provides a thorough and practical introduction to the entire network infrastructure, from cabling to the routers. What you need to learn to pass a Cisco certification exam such as CCNA and what you need to know to survive in the real world are two very different things. The strategies that this book offers weren 't on the exam, but they 're exactly what you need to do your job well.