Top 10 books to read and gain a deeper understanding of how networking works (or doesn't).

I am in a position at work where I'm supposed to know all about our domain and the users and policies and permissions and DHCP and, and, and...

I've learned ALOT by the seat-of-my-pants but - since I love to read - I'd like to know what you all would suggest as "good to have" books.

I'd love to see you all answer the "if I could only have ONE book ..." question.

I'll bump points as replys  come in.