The Second Edition of this best-selling text continues to answer the question, "How do computer networks and internets operate?" Douglas Comer, a leading computer networking authority, provides a self-contained tour from the lowest levels of data transmission wiring through the highest levels of application software, explaining how facilities and services are used and extended in the next level. Finally, the text explains how applications use reliable stream transfer to provide high-level services. Computer Networks and Internets is appropriate for use by undergraduate students, as well as graduate students and professionals with little or no background in networking or operating systems. The text uses analogies and examples to define concepts instead of sophisticated mathematical proofs.