Data Communications and Networking This book provides a detailed look at the subject and covers everything, right from the basics of the subject of data communication and networking. Its bottom-up approach makes this book appropriate even for students who do not have any knowledge of networking or telecommunication. With the explosive increase in the usage of computers and networking systems, data communication and networking technologies are advancing at a fast pace. As the use of these technologies has become increasingly common, the need to cultivate an understanding of these technologies is also on the increase. Students and professionals from various study streams, specializations, and backgrounds now take courses on data communication and networking. Not all of them may have previous knowledge of data communication and telecommunication concepts, and keeping this in mind, this book begins with the basics of the technology and slowly builds on the same. This book uses the five layer TCP/IP protocol suite as the framework for the text. It begins with an introduction to the technologies of networking and data communication. The section provides an overview of network topologies, types of networks, and an overview of the Internet. The next chapter focuses on the major network protocols, OSI and TCP/IP. Further, the book has been divided into sections that talk about the five layers of Internet architecture - the Physical Layer, Data Link Layer, Network Layer, Transport Layer, and Application Layer. The Physical Layer section explains aspects of telecommunication that are relevant to the Physical Layer. It takes a look at transmission media and switching and provides an overview of how telephone and cable TV networks can be used for data communication. The Data Link Layer section covers error detection and corrections, data link control concepts, and Local Area Networks (LANs) and Wide Area Networks (WANs). The Network Layer section focuses on topics like IP address and Network Layer protocols like IP, ICMP, ARP, and IGMP. This section also explains delivery, routing, and forwarding of data packets. The Transport Layer section provides an overview of the functionalities of this layer. It provides an introduction to the transport layer protocols - TCP, UDP, and SCTP.The section also discusses the issues of congestion and quality of service. The Application Layer section focuses on the Domain Name System (DNS). This technology is used to map application layer addresses to network layer addresses. It also takes a look at the World Wide Web (WWW) and the HTTP and SNMP protocols. The section also explains remote logging, e-mail, and file transfer There is a separate section on security in this book, and it discusses topics like cryptography, network security, and Internet-related security concepts like firewalls, VPN, SSL/TLS etc. The book has a large number of illustrations and pictures that greatly help in explaining the concepts covered. The author uses real-life examples in relevant sections and important points are emphasized in highlighted boxes. Each chapter ends with a summary, a list of key terms, practice sets of questions and exercises, and a section on recommended reading for further knowledge on the topics covered. The Appendix contains review and quick reference material. The book ends with a comprehensive set of glossary and acronyms. About Behrouz A. Forouzan Behrouz A. Forouzan is an expert on computers systems, networking, databases, and programming. Some of the books written by Behrouz A. Forouzan are Data Structures: A Pseudocode Approach with C, Computer Science: A Structured Approach Using C , C Programming: A Problem-Solving Approach, TCP/IP Protocol Suite , and Unix and Shell Programming: A Textbook. He is a Professor at DeAnza College in Cupertino, California. Born in 1944, he graduated from the University of California. He has written a number of books on his fields of expertise.