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 ? How do Protocols ensure that services runningon one kind of device can send to and receivefrom many different network devices? How can you use network analysis tools toexamine and explain how common user applications work?Key TermsThis chapter uses the following key terms.

OSI Layers 5, 6, and 7. A comparison of the OSI and TCP/IP model is shown in Figure 3-3. Figure 3-3 OSI and TCP/IP Model Most TCP/IP application layer protocols were developed before the emergence of personal computers, GUIs, and multimedia objects. As a result, these protocols implement little of

  Applications, Protocol, Early, Application layer, Application layer protocols