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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.
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英文网站做SEO和中文的是一样的，英文站主要优化的是Google，关注谷歌排名就可以了英文网站优化，对于你说的关键词选择，建议如下几点:1、使用谷歌的关键词选取工具，精准的选择产品热门关键词2、分析下竞争对手的网站关键词，看看他们是怎么选择关键词的而至于你说的优化，只要网站做好了，内链、外链，都正常的做就可以了
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1、英文网站SEO优化主题一定要明确在做英文网站之前一定要做一下规划,做英文网站之前，定位是非常重要的要做什么产品,什么样的关键词,如何确实关键词的转化效果.还有一点，在网上看到的，就是要专，细分到具体方面，一个小的主题比较好做，竞争也不是很大。当然，能选择跟产品和服务有关的主题，搜索引擎优化也是非常重要的一项。2、英文网站SEO选域名很关键当然，能用.com域名来做英文站SEO是肯定不会错的，但如果网站是想让老外一看到就知道是中国的站，用CN是最佳选择，不过一般情况下最好用.com。3、英文站的友情链接这一点在英文SEO中比较麻烦，主要是缺少资源、链接资源、或者说缺少朋友，内容在友情链接方面也有很大的作用。4、英文网站SEO如何做好网站内容国内大多数英文站的内容，很少有原创的，伪原创的居多，但这样一来就给自己的网站定位为垃圾站了，根本谈不上长远发展，更有甚者采用英文站采集。5、英文网站如何进行内部优化英文站的优化比中文SEO更容易，国外SEO专家的网站，他们写文章的格式跟国内也很不一样。title+descrition+h1+(h3+内容)+(h3+内容)+(h3+内容)，很多人喜欢用动力生成的文章内容链接，但这样一来就降低了网站的用户体验,英文网站内部优化大家可以多跟优化做的比较好的网站学习,从他们的源码和关键词布局来不断的总结学习。 6、用户访问的习惯
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