计算机科学引论课后习题

121820080140081804WillardP311.DescribehowtheInternetandtheWebstarted.A:Theinternetwaslaunchedin1969whentheUnitedStatesfundedaprojectthatdevelopedanationalcomputernetworkcalledAdvancedResearchProjectAgencyNetwork(ARPANET).TheWebwasintroducedin1992attheCenterforEuropeanNuclearresearch(CERN)inSwitzerland.Fromtheseearlyresearchbeginnings,theInternetandtheWebhaveevolvedintooneofthemostpowerfultoolsofthe21stcentury.2.WhatisthedifferencebetweentheInternetandtheWeb?A:TheInternetistheactualphysicalnetwork.Itismadeupofwires,cables,andsatellites.AndtheWebisamultimediainterfacetotheresourcesavailableontheInternet.3.ListanddescribefiveofthemostcommonusesoftheInternetandtheWeb.A:Themostcommonusesarethefollowing:CommunicatingisbyfarthemostpopularInternetactivity.Shoppingisoneofthefastest-growingInternetapplications.Searchingforinformationhasneverbeenmoreconvenient.Entertainmentoptionsarenearlyendless.Educationore-learningisanotherrapidlyemergingWebapplication.P331.WhatisthefunctionofanISP?DescribetwotypesofISPs.A:TheISPareInternetserviceprovider.ItisconnectedtotheInternetandprovideapathorconnectionforindividualstoaccesstheInternet.ThetwotypesofISPsareNationalserviceprovidersandwirelessserviceproviders.Nationalserviceprovidersprovideaccessthroughstandardtelephoneorcableconnections.UserscanaccesstheInternetfromalmostanywherewithinthecountryforastandardfeewithoutincurringlong-distancetelephonecharges.Wirelessserviceprovidersdonotusetelephoneorcablelines.TheyprovideInternetconnectionsforcomputerswithwirelessmodemsandawidearrayofwirelessdevices.2.Whatisthefunctionofabrowser?A:BrowsersareprogramsthatprovideaccesstoWebresources.3.WhatareURLs,HTML,Webpages,hyperlinks,applets,andJava?A:Forbrowserstoconnecttoresources,thelocationoraddressoftheresourcesmustbespecified.TheseaddressarecalledURLsTheHTMLisHypertextMarkupLanguagecommandstointerpretstheweb.Thewebpagesarepresentinformationaboutthesitealongwithreferencesandhyperlinkorlink.Thehyperlinksarethelinksthatconnecttootherdocumentscontainingrelatedinformation—textfiles,graphicimages,audio,andvideoclips.Theappletsarethetypicallywritteninaprogramminglanguage.Itcanbedownloadedquicklyandrunbymostbrowsers.TheJavaaretheprogramminglanguagewrittenappletswidelyusedtoaddinterestandactivitytoaWebsitebypresentinganimation,displayinggraphics,providinginteractivegames,andmuchmore.P391.Definee-mail.Whatarethethreebasicelementsofatypicale-mailmessage?A:E-mailorelectronicmailisthetransmissionofelectronicmessagesovertheInternet.Thethreebasicelementsare:header,message,andsignature.2.Whatisspam?Whatarespamblocks?A:Therearemanyunwantedandunsolicitede-mails.Thisunwelcomemailiscalledspam.Thespamblocksisuseavarietyofdifferentapproachestoidentifyandeliminatespam.3Whatisinstantmessaging?Howisitdifferentfrome-mail?A:Instantmessagingisanextensionofe-mailthatallowstwoormorepeopletocontacteachotherviadirect,livecommunication.Byinstantmessagingyoucansendmessagesdirectlybackandforthtooneanotherismorequicklythane-mail.4.Whatissocialnetworking?Discussreuniting,friend-of-a-friend,andcommoninterestsites.A:Thesocialnetworkingisconnectingindividualstooneanother.Therearethreebasiccategoriesofsocialnetworkingsites:reuniting,friend-of-a-friend,andcommoninterest.Reunitingsitesaredesignedtoconnectpeoplewhohaveknownoneanotherbuthavelosttouch.Friend-of-a-friendsitesaredesignedtobringtogethertwopeoplewhodonotknowoneanotherbutshareacommonfriend.Commoninterestsitesbringtogetherindividualsthatsharecommoninterestsorhobbies.P421.Whatisthedifferencebetweenasearchengineandametasearchengine?A:SearchenginesarespecializedprogramsthatassistyouinlocatinginformationontheWebandtheInternet.Metasearchenginesareprogramsthatautomaticallysubmityoursearchrequesttoseveralsearchenginessimultaneously.2.Whatisaspecializedsearchengine?Whenwouldaspecializedsearchenginebeuseful?A:Specializedsearchenginesfocusonsubject-specificWebsites.Itcanpotentiallysaveyoutimebynarrowingyoursearch.Foralistofjustafewselectedspecializedsearchengines.Whenyouaresearchsomesubject-specificlikethesisitcanbeuseful.3.WhatarethefourconsiderationsforevaluatingWebsitecontent?A:Thefourconsiderationsisauthority,accuracy,objectivityandcurrency.P421.Whatiselectroniccommerce?A:Electroniccommerce,alsoknownase-commerce,isthebuyingandsellingofgoodsovertheInternet.2.Whatarethethreebasictypesofe-commerce?A:Therearebusiness-to-consumer,consumer-to-consumerandbusiness-to-business.3.Whatarethethreebasicoptionsforelectronicpayment?A:Thethreebasicpaymentoptionsarecheck,creditcard,andelectroniccash.P481.WhatareWebutilities?Web-basedapplications?FTP?A:WebutilitiesarespecializedutilityprogramsthatmakeusingtheInternetandtheWebeasierandsafer.Web-basedapplicationsareownedbyindividualsororganizationsandstoredontheircomputersystem’sharddisks.ThisfreeserviceprovidesaccesstoprogramswithcapabilitiessimilartoMicrosoft’sWord,Excel,andPowerPoint.Filetransferprotocol(FTP)isanInternetstandardfortransferringfilestocopyfilesfromyourcomputertoanothercomputerontheInternet.2.Whatareplug-insandfiltersusedfor?A:Plug-i