迷茫的前途
WhatisaNetwork?Anetworkconsistsoftwoormorecomputersthatarelinkedinordertoshareresources(suchasprintersandCDs),exchangefiles,orallowelectroniccommunications.Thecomputersonanetworkmaybelinkedthroughcables,telephonelines,radiowaves,satellites,orinfraredlightbeams.Thetwobasictypesofnetworksinclude:LocalAreaNetwork(LAN)WideAreaNetwork(WAN)YoumayalsoseereferencestoaMetropolitanAreaNetworks(MAN),aWirelessLAN(WLAN),oraWirelessWAN(WWAN).LocalAreaNetworkALocalAreaNetwork(LAN)isanetworkthatisconfinedtoarelativelysmallarea.Itisgenerallylimitedtoageographicareasuchasawritinglab,school,orbuilding.RarelyareLANcomputersmorethanamileapart.InatypicalLANconfiguration,onecomputerisdesignatedasthefileserver.Itstoresallofthesoftwarethatcontrolsthenetwork,aswellasthesoftwarethatcanbesharedbythecomputersattachedtothenetwork.Computersconnectedtothefileserverarecalledworkstations.Theworkstationscanbelesspowerfulthanthefileserver,andtheymayhaveadditionalsoftwareontheirharddrives.OnmanyLANs,cablesareusedtoconnectthenetworkinterfacecardsineachcomputer;otherLANsmaybewireless.SeetheTopology,Cabling,andHardwaresectionsofthistutorialformoreinformationontheconfigurationofaLAN.WideAreaNetworkWideAreaNetworks(WANs)connectlargergeographicareas,suchasFlorida,theUnitedStates,ortheworld.Dedicatedtransoceaniccablingorsatelliteuplinksmaybeusedtoconnectthistypeofnetwork.UsingaWAN,schoolsinFloridacancommunicatewithplaceslikeTokyoinamatterofminutes,withoutpayingenormousphonebills.AWANiscomplicated.ItusesmultiplexerstoconnectlocalandmetropolitannetworkstoglobalcommunicationsnetworksliketheInternet.Tousers,however,aWANwillnotappeartobemuchdifferentthanaLAN.AdvantagesofInstallingaSchoolNetworkSpeed.Networksprovideaveryrapidmethodforsharingandtransferringfiles.Withoutanetwork,filesaresharedbycopyingthemtomemorycardsordiscs,thencarryingorsendingthediscsfromonecomputertoanother.Thismethodoftransferringfiles(referredtoassneaker-net)canbeverytime-consuming.Cost.Networkableversionsofmanypopularsoftwareprogramsareavailableatconsiderablesavingswhencomparedtobuyingindividuallylicensedcopies.Security.Filesandprogramsonanetworkcanbedesignatedas"copyinhibit,"sothatyoudonothavetoworryaboutillegalcopyingofprograms.Also,passwordscanbeestablishedforspecificdirectoriestorestrictaccesstoauthorizedusers.CentralizedSoftwareManagement.Oneofthegreatestbenefitsofinstallinganetworkataschoolisthefactthatallofthesoftwarecanbeloadedononecomputer(thefileserver).Thiseliminatesthatneedtospendtimeandenergyinstallingupdatesandtrackingfilesonindependentcomputersthroughoutthebuilding.ResourceSharing.Sharingresourcesisanotheradvantageofschoolnetworks.Mostschoolscannotaffordenoughlaserprinters,faxmachines,modems,scanners,andCDplayersforeachcomputer.However,iftheseorsimilarperipheralsareaddedtoanetwork,theycanbesharedbymanyusers.ElectronicMail.Thepresenceofanetworkprovidesthehardwarenecessarytoinstallane-mailsystem.E-mailaidsinpersonalandprofessionalcommunicationforallschoolpersonnel,anditfacilitatesthedisseminationofgeneralinformationtotheentireschoolstaff.ElectronicmailonaLANcanenablestudentstocommunicatewithteachersandpeersattheirownschool.IftheLANisconnectedtotheInternet,studentscancommunicatewithothersthroughouttheworld.FlexibleAccess.Schoolnetworksallowstudentstoaccesstheirfilesfromcomputersthroughouttheschool.Studentscanbeginanassignmentintheirclassroom,savepartofitonapublicaccessareaofthenetwork,thengotothemediacenterafterschooltofinishtheirwork.Studentscanalsoworkcooperativelythroughthenetwork.WorkgroupComputing.Collaborativesoftwareallowsmanyuserstoworkonadocumentorprojectconcurrently.Forexample,educatorslocatedatvariousschoolswithinacountycouldsimultaneouslycontributetheirideasaboutnewcurriculumstandardstothesamedocument,spreadsheets,orwebsite.DisadvantagesofInstallingaSchoolNetworkExpensivetoInstall.Althoughanetworkwillgenerallysavemoneyovertime,theinitialcostsofinstallationcanbeprohibitive.Cables,networkcards,routers,andsoftwareareexpensive,andtheinstallationmayrequiretheservicesofatechnician.RequiresAdministrativeTime.Propermaintenanceofanetworkrequiresconsiderabletimeandexpertise.Manyschoolshaveinstalledanetwork,onlytofindthattheydidnotbudgetforthenecessaryadministrativesupport.FileServerMayFail.Althoughafileserverisnomoresusceptibletofailurethananyothercomputer,whenthefilesserver"goesdown,"theentirenetworkmaycometoahalt.Whenthishappens,theentireschoolmayloseaccesstonecessaryprogramsandfiles.CablesMayBreak.TheTopologychapterpresentsinformationaboutthevariousconfigurationsofcables.Someoftheconfigurationsaredesignedtominimizetheinconvenienceofabrokencable;withotherconfigurations,onebrokencablecanstoptheentirenetwork.MustMonitorSecurityIssues.Wirelessnetworksarebecomingincreasinglycommon;however,securitycanbeanissuewithwirelessnetworks.
dp73754458
I can read e-books on the computer. 我可以在电脑上看电子书.I can write an e-mail on the computer. 我可以在电脑上写邮件.I can send e-mail through the internet. 我能通过因特网发送邮件.I can have personal information on the net. 我可以在网上公布个人信息.I can find out some informations on the net.我也可以在网上找到一些信息.I can chat with my friend on the computer.我能在电脑上和朋友聊天.I make my friend through a computer net-chat.我通过网上聊天交朋友.After school,I often go online and chat with my friends.放学后,我常常上网和朋友聊天.In fact,shopping online is really easy and fast.I prefer shopping online.事实上,网上购物非常简单快捷,我更喜欢网上购物.Sometimes,I play computer games.有时我也会玩电脑游戏.
紜亦眠观520
People can shop online 购物People can contact through the Internet 联络People can learn through the Internet 学习People can play online 娱乐求采纳
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