The textbook for COMP476 Networked Computer Systems is

 

Computer Networks and Internets, 5th edition, by Douglas E. Comer, Prentice Hall, 2009,
ISBN: 0-13-606127-3

 

The textbook is available at the A&T Bookstore for $127.00 new

 

You can also find the textbook at many online bookstores.  The following search engines will locate the text at several online bookstores

http://www.chambal.com

http://www.dealoz.com

 

If you buy the textbook online, I strongly suggest you pay extra for fast shipping.

 

The 5th edition of the textbook moves and improves the chapters from the 4th edition.  A rough mapping of the chapters between the 4th and 5th editions can be found here.