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Chapter 1 1

Application Layer

Functionality andProtocols

Network Fundamentals

Chapter 3

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Objectives Define the application layer as the source and

destination of data for communication acrossnetworks.

Explain the role of protocols in supportingcommunication between server and clientprocesses.

Describe the features, operation, and use of

well-known TCP/IP application layer services(HTTP, DNS, SMTP).

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Applications The Interface BetweenHuman 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 BetweenHuman and Data Networks The role of applications, services and protocols in converting

communication to data that can be transferred across the datanetwork

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Applications The Interface BetweenHuman and Data Networks Roles applications, services and protocols play in transporting data

through networks

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Applications The Interface BetweenHuman and Data Networks The role protocols play in networking and identify several message

properties that can be defined by a protocol

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The Role of Protocols in Supporting

Communication Roles of client and server processes in data networks

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The Role of Protocols in SupportingCommunication Common Application Layers services and protocols

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The Role of Protocols in SupportingCommunication Compare and contrast client server networking with peer-to-peer

networking and peer-to-peer applications

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Features, Operation, and Use of TCP/IPApplication Layer Services Features of the DNS protocol and how this protocol supports DNS

services

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Features, Operation, and Use of TCP/IPApplication Layer Services Features of the HTTP protocol and how this protocol supports the

delivery of web pages to the client

GET Client Request For DataPUT & POST Upload the data to the web server

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Features, Operation, and Use of TCP/IPApplication Layer Services Features of the Telnet protocol and identify several of its uses in

examining and managing networks

Telnet Daemon

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Features, Operation, and Use of TCP/IPApplication Layer Services Features of the SMB(Server Message Block) protocol and the role

it plays in supporting client/server file sharing in Microsoft-basednetworks. Linux SAMBA

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Features, Operation, and Use of TCP/IPApplication Layer Services

SMB messages can:

Start, authenticate, and terminate sessions

Control file and printer access

Allow an application to send or receive messages to orfrom another device

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Features, Operation, and Use of TCP/IPApplication Layer Services Features of the Gnutella protocol and the role it plays in supporting

P2P services

Sharing files over the Internet has become extremelypopular.With P2P applications based on the Gnutella protocol,people can make files on their hard disks available toothers for downloading.Gnutella-compatible client software allows users toconnect to Gnutella services over the Internet and tolocate and access resources shared by other Gnutellapeers.

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Features, Operation, and Use of TCP/IPApplication Layer Services

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Features, Operation, and Use of TCP/IPApplication Layer Services

The Gnutella protocol defines five different packet types:

ping - for device discovery

pong - as a reply to a ping

query - for file location

query hit - as a reply to a query

push - as a download request

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