In a hurry? Start here,

This book has been recommended for beginners. That is true. You don’t have to wade through a bunch of theory to get to the meat of administration.

The same is true for experienced administrators. This book will point you in the direction to go when you are using the real manuals.

Take some time and slowdown to try some of the examples. Then when you need them you will have already mastered that section.

I have several other books now and know a lot of what is in this one. However I would feel naked if this was not reachable.

A complementary book would be Practical Unix and Internet Security.