Many books about TCP/IP and the Internet are available from your local library or computer bookstore. Three highly recommended books are
Craig Hunt. TCP/IP Network Administration - This book contains some theory and much practical information for managing a heterogeneous TCP/IP network.
W. Richard Stevens. TCP/IP Illustrated, Volume I - This book is an in-depth explanation of the TCP/IP protocols. It is ideal for network administrators requiring a technical background in TCP/IP and for network programmers.
Ed Krol. The Whole Internet User's Guide & Catalog - This book is ideal for anyone interested in using the many tools available for retrieving information over the Internet.