Application Layer Functionality and Protocols

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CHAPTER 3Application Layer Functionality and ProtocolsObjectivesUpon completion of this chapter, you will be able to answer the following questions: How do the functions of the three upper OSImodel layers provide network services to end-user applications ? How do the TCP/IP Application Layer protocolsprovide the services specified by the upper layers of the OSI model ? How do people use the Application Layer to communicate across the information network? What are the functions of well-known TCP/IPapplications, such as the World Wide Web and e-mail, and their related services (HTTP, DNS,DHCP, STMP/POP, and Telnet)? What are the file-sharing processes that usepeer-to-peer applications and the Gnutella protocol?

The OSI model is a seven-layer model, designed to help explain the flow of information from layer to layer. Figure 3-1 Interfacing Human and Data Networks This chapter focuses on the role of Layer 7, the application layer, and its components: applications, services, and protocols. You explore how these three elements make the robust

  Applications, Model, Early, Seven, Osi model, Application layer, Relay models