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Application Layer Functionality and Protocols

Network Fundamentals – Chapter 3

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Objectives Define the application layer as the source and

destination of data for communication across networks.

Explain the role of protocols in supporting communication between server and client processes.

Describe the features, operation, and use of well-known TCP/IP application layer services (HTTP, DNS, SMTP).

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Applications – The Interface Between Human and Data Networks Applications provide the means for generating and receiving data

that can be transported on the network

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Applications – The Interface Between Human and Data Networks Applications, Services and Protocols are required to convert

communication to data that can be transferred across the data network

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Applications – The Interface Between Human and Data Networks

When you open an, the application is started and the program is loaded into the device memory where it executes

Each “executing” program is referred to as a PROCESS

Some Applications build in PROTOCOLS within the application to support network communication

SERVICES are the interfaces to access an Application that resides on a server.

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Applications – The Interface Between Human and Data Networks

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Applications – The Interface Between Human and Data Networks Protocols play a major role in networking

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The Role of Protocols in Supporting Communication Describe the roles of client and server processes in data networks

Clients initiate data exchange

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The Role of Protocols in Supporting Communication List common Application Layers services and protocols

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Features, Operation, and Use of TCP/IP Application Layer Services Describe the features of the DNS protocol and how this protocol

supports DNS services

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Describe the features of the HTTP protocol and how this protocol supports the delivery of web pages to the client.

The two protocols used to control the transfer from server to client are HTTP (80) HTTP (443)

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POP (110) and SMTP (25) support e-mail services

MTA receives email from the client's MUA, uses SMTP to route email between servers and delivers email to clients via the POP3 protocol

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Describe the features of the Telnet (23) protocol and identify several of its uses in examining and managing networks

SSH (22) serves same function but encrypts the data

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SMB is a Client/Server file sharing protocol for Windows

Unlike the file sharing supported by FTP, clients establish a long term connection to servers. Once the connection is established, the user of the client can access the resources on the server as if the resource is local to the client host.

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In P2P networks, computer that responds to a file sharing request is functioning as a server.

Security is difficult to enforce resources are decentralized

Resource sharing without a dedicated server

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Summary

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