Mike Meyers’ CompTIA network+ guide to Managing and Troubleshooting Networks / Mike Meyers, McGraw-Hill, 2009
If you want to get certified, here is your book. It is quite useful in any case. And the pictures add value: did you know what an F-connector on coax looks like? (It’s what connects your satellite TV dish, or your broadband wireless antenna. 500 pages, large format.