© 2007 Prentice-Hall, Inc. 1 Technology in Action 1.

1 © 2007 Prentice-Hall, Inc.

Technology in ActionTechnology in Action

1


Technology in ActionTechnology in Action

Chapter 13Chapter 13

Behind the Scenes: Behind the Scenes:

The Internet: How It WorksThe Internet: How It Works


Chapter TopicsChapter Topics

• Managing the InternetManaging the Internet• Interaction between Internet componentsInteraction between Internet components• Internet data transmission and protocolsInternet data transmission and protocols• IP addresses and domain namesIP addresses and domain names• FTP and TelnetFTP and Telnet• HTML and XLMHTML and XLM• How e-mail and instant messaging work How e-mail and instant messaging work

and how to keep them secureand how to keep them secure


Management of the InternetManagement of the Internet

Who owns the Internet?Who owns the Internet?– IndividualsIndividuals– UniversitiesUniversities– Government agenciesGovernment agencies– Private companiesPrivate companies

Who manages the Who manages the Internet?Internet?– Nonprofit organizationsNonprofit organizations– User groupsUser groups

Who pays for the Who pays for the Internet?Internet?

– U.S. taxpayersU.S. taxpayers– BusinessesBusinesses– UniversitiesUniversities– Other countriesOther countries


Internet NetworkingInternet Networking• A network of networksA network of networks

– Worldwide network of Worldwide network of computer systemscomputer systems

• ProtocolProtocol– Set of rules for Set of rules for

communicatingcommunicating– All computers connected to the Internet All computers connected to the Internet

use common protocols so they can use common protocols so they can understand one anotherunderstand one another


Network HierarchyNetwork Hierarchy• Tier 1Tier 1

– Internet backboneInternet backbone– Move large amounts of dataMove large amounts of data– Provide access to regional ISPsProvide access to regional ISPs

• Tier 2Tier 2– Regional ISPsRegional ISPs– Provide access to local ISPsProvide access to local ISPs

• Tier 3Tier 3– Local ISPsLocal ISPs– Provide Internet access to homes Provide Internet access to homes

and businessesand businesses


T LinesT Lines

• High speed fiber-optic linesHigh speed fiber-optic lines• T-1 linesT-1 lines

– 24 simultaneous voice or data 24 simultaneous voice or data channelschannels

– 1.544 Mbps throughput1.544 Mbps throughput

• T-2 linesT-2 lines– 4 T-1 lines4 T-1 lines– 6.3 Mbps throughput6.3 Mbps throughput




Network Access Points (NAPs)Network Access Points (NAPs)

• Points of connection between ISPsPoints of connection between ISPs

• Routers move data between networksRouters move data between networks


Points of Presence (POP)Points of Presence (POP)

• Bank of modems where individual users Bank of modems where individual users connect to an ISPconnect to an ISP


The Network Model of the InternetThe Network Model of the Internet

• Internet communications follows the client/server Internet communications follows the client/server network modelnetwork model

• Clients request servicesClients request services• Servers respond to requestsServers respond to requests• Types of servers includeTypes of servers include

– Web serversWeb servers• Host Web pagesHost Web pages

– Commerce serversCommerce servers• Enable the purchase of goods and services over the InternetEnable the purchase of goods and services over the Internet

– File serversFile servers• Provide remote storage space for files that users Provide remote storage space for files that users

can downloadcan download


P2P File sharingP2P File sharing


Data Transmission and ProtocolsData Transmission and Protocols

• Computer protocols are rules for electronic Computer protocols are rules for electronic information exchangeinformation exchange

• Open system protocolsOpen system protocols– Any computer can communicate with other Any computer can communicate with other

computers using the same protocolscomputers using the same protocols


Circuit SwitchingCircuit Switching

• Dedicated connection between two pointsDedicated connection between two points

• Remains active until the transmission is Remains active until the transmission is terminatedterminated

• Used in telephone communicationsUsed in telephone communications


Packet SwitchingPacket Switching

• Data is broken into small units called packetsData is broken into small units called packets• Packets are sent over various routes to their Packets are sent over various routes to their

destinationdestination• Packets are reassembled by the receiving Packets are reassembled by the receiving

computercomputer• Packets containPackets contain

– Destination/source addressesDestination/source addresses– Reassembling instructionsReassembling instructions– Data Data


Packet SwitchingPacket Switching


TCP/IPTCP/IP

• Transmission Control Protocol (TCP)Transmission Control Protocol (TCP)– Prepares data for transmissionPrepares data for transmission– Provides error checkingProvides error checking– Enables resending lost dataEnables resending lost data

• Internet Protocol (IP)Internet Protocol (IP)– Responsible for sending data from one Responsible for sending data from one

computer to anothercomputer to another


IP AddressesIP Addresses

• Unique number that identifies devices Unique number that identifies devices connected to the Internetconnected to the Internet

• Typical IP addressTypical IP address– 197.24.72.157197.24.72.157

• Static addressStatic address– Address never changesAddress never changes

• Dynamic addressDynamic address– Temporary addressTemporary address


Domain NamesDomain Names

• Name that takes the place of an IP addressName that takes the place of an IP address• Sample domain nameSample domain name

– www.mywebsite.comwww.mywebsite.com• Top-level domains (TLD)Top-level domains (TLD)

– Portion of the domain name that follows the dotPortion of the domain name that follows the dot– Sample top-level domain namesSample top-level domain names

• .com.com, , .org.org, , .edu.edu, and , and .net.net

• Second-level domainsSecond-level domains– Unique name within a top-level domainUnique name within a top-level domain– Sample second-level domain namesSample second-level domain names

• Yahoo.comYahoo.com, , Google.comGoogle.com, and , and Unesco.orgUnesco.org


DNSDNSDomain Name ServerDomain Name Server

• Internet servers that translate domain names to IP addressesInternet servers that translate domain names to IP addresses• ISPs go first to a default DNS to resolve a nameISPs go first to a default DNS to resolve a name• Name queries work up the hierarchy to the root DNS servers if Name queries work up the hierarchy to the root DNS servers if

requiredrequired


Other ProtocolsOther Protocols

• File Transfer Protocol (FTP)File Transfer Protocol (FTP)– File-sharing protocolFile-sharing protocol– Files are downloaded and uploaded using Files are downloaded and uploaded using

the Internetthe Internet

• TelnetTelnet– Protocol for connecting to a remote computer Protocol for connecting to a remote computer

and a TCP/IP serviceand a TCP/IP service– Enables a client computer to control a server Enables a client computer to control a server

computercomputer


HTTP and SSLHTTP and SSL

• Hypertext Transfer ProtocolHypertext Transfer Protocol– Protocol for transferring hypertext documentsProtocol for transferring hypertext documents– Hypertext documents are linked to other Hypertext documents are linked to other

documents (through hyperlinks) documents (through hyperlinks)

• Secure Socket LayerSecure Socket Layer– Security protocols that protect sensitive Security protocols that protect sensitive

informationinformation– Encrypts dataEncrypts data


HTML/XHTMLHTML/XHTML• Hypertext Markup Language (HTML)Hypertext Markup Language (HTML)

– Format for creating Web pagesFormat for creating Web pages• Extensible Hypertext Markup Language (XHTML)Extensible Hypertext Markup Language (XHTML)

– Current version of HTMLCurrent version of HTML– Has much more stringent rules than HTML regarding taggingHas much more stringent rules than HTML regarding tagging

• HTML/XHTML are not programming languages but sets of rules for marking up blocks of HTML/XHTML are not programming languages but sets of rules for marking up blocks of text so that a browser knows how to display them text so that a browser knows how to display them

HTML/XHTML ExampleHTML/XHTML Example

<h1>This is the Heading</h1>

This is text using Arial font.

This text is italicized.

This text is bold.

This text color is red.

This is a hyperlink <a href="http://vig.prenhall.com/">www.prenhall.com</a>

HTML/XHTML Web Page Display


Common Gateway Interface (CGI)Common Gateway Interface (CGI)• Browsers request that a Browsers request that a

program file executes program file executes (runs)(runs)

• CGI files often called CGI files often called CGI scriptsCGI scripts

• Adds Web page Adds Web page interactioninteraction– Adding names to guest Adding names to guest

books/mailing listsbooks/mailing lists– Completing formsCompleting forms


Client-Side ApplicationsClient-Side Applications

• A program that runs on a client computer with no A program that runs on a client computer with no interaction with the serverinteraction with the server

• Types of client-side applications includeTypes of client-side applications include– HTML/XHTML document embedded with JavaScript codeHTML/XHTML document embedded with JavaScript code– Applet: Small program that resides on the serverApplet: Small program that resides on the server


Extensible Markup Language Extensible Markup Language (XML)(XML)

• Designed for information exchangeDesigned for information exchange

• Tools used to create your own markup Tools used to create your own markup languagelanguage

• Used in e-commerce transactionsUsed in e-commerce transactions


Communications Over the InternetCommunications Over the Internet

• E-mailE-mail– Created in 1971 by Created in 1971 by

Ray TomlinsonRay Tomlinson– Simple Mail Simple Mail

Transfer Protocol Transfer Protocol (SMTP)(SMTP)

– Multipurpose Multipurpose Internet Mail Internet Mail Extensions (MIME): Extensions (MIME): Protocol for Protocol for attaching files to e-attaching files to e-mailmail


Communications Over the InternetCommunications Over the Internet

• E-mail securityE-mail security– Encryption Encryption

• Private-key encryptionPrivate-key encryption• Public-key encryptionPublic-key encryption

– Secure data transmission softwareSecure data transmission software• SafeMessage SafeMessage


Instant Messaging (IM)Instant Messaging (IM)• Client/server application program for real-Client/server application program for real-

time, text-based conversationstime, text-based conversations

• Popular instant messaging programsPopular instant messaging programs– AOL Instant MessengerAOL Instant Messenger– ICQICQ– Yahoo! MessengerYahoo! Messenger– Windows MessengerWindows Messenger


Chapter 13 Summary QuestionsChapter 13 Summary Questions

• What data transmissions and protocols What data transmissions and protocols does the Internet use?does the Internet use?



• How do the Internet’s networking How do the Internet’s networking components interact?components interact?



• What data transmissions and protocols What data transmissions and protocols does the Internet use?does the Internet use?



• Why are IP addresses and domain names Why are IP addresses and domain names important for Internet communications?important for Internet communications?



• What are FTP and Telnet and how do I What are FTP and Telnet and how do I use them?use them?



• What are HTML and XML used for?What are HTML and XML used for?



• How do e-mail and instant messaging How do e-mail and instant messaging work and how are messages kept secure?work and how are messages kept secure?

© 2007 Prentice-Hall, Inc. 1 Technology in Action 1.

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Transcript of © 2007 Prentice-Hall, Inc. 1 Technology in Action 1.