Networking technologies and practices are constantly evolving. Equip your students with an understanding that helps them keep pace with Internet time. In this carefully focused revision of the best-selling first edition, authors Peterson and Davie reiterate their commitment to a systems-oriented approach to networking instruction. Focusing on the why of network design-not just the specifications comprising today's systems but how key technologies and protocols actually work in the real world to solve specific problems-they promote an enduring, practical understanding of networks and their building blocks. The second edition incorporates coverage of Quality of Service issues, mobile and wireless networks, VPNs, and much more. Over 100 new exercises help users consolidate and expand their knowledge.