【文档说明】计算机专业英语23-Uniform-Resource-Locators课件.pptx，共(12)页，9.311 MB，由小橙橙上传

转载请保留链接：https://www.ichengzhen.cn/view-77568.html

以下为本文档部分文字说明：

LessonUniformResourceLocators231.Canyoulistsometop-leveldomainnames?2.Whatdoes“www”standfor?Warm-upExercisesURL统一资源定位器human-r

eadable人们可读的machine-readable机器可读的IP（IP协议）top-level顶级unique独特，唯一left-most最左convert转换WordPreparationWhenyouusetheWeborsendane-mailmessage,youuseadomai

nnametodoit.Forexample,theUniformResourceLocator(URL)"http://www.Yiren.com"(readash-t-t-p-colon-slash-slash

(ordoubleslash)-w-w-w-dot-….)containsthedomainnameYiren.com.Sodoesthise-mailaddress:example@Yiren.com.Everytimeyouuse

adomainname,youusetheInternet'sDNSserverstotranslatethehuman-readabledomainnameintothemachine-readableIPaddress.Text每次使用

域名时，要用Internet的DNS服务器将可读域名变成机器可读的IP地址Top-leveldomainnames,alsocalledfirst-leveldomainnames,include.COM,.ORG,.NET,

.EDUand.GOV.Withineverytop-leveldomainthereisahugelistofsecond-leveldomains.Forexample,inthe.COMfirst-leveldomainthereis:YirenYahooMicrosoftEve

rynameinthe.COMtop-leveldomainmustbeunique.Theleft-mostword,likewww,isthehostname.Itspecifiesthenameofaspecificmachine(withaspecificIPaddr

ess)inadomain.Agivendomaincan,potentially,containmillionsofhostnamesaslongastheyarealluniquewithinthatdomain.Text给定域中可能有几百万个主机名，只要它们在

域中全部唯一DNSserversacceptrequestsfromprogramsandothernameserverstoconvertdomainnamesintoIPaddresses.Whenarequestcomesin,theDNSservercandooneoffourth

ingswithit:1.ItcananswertherequestwithanIPaddressbecauseitalreadyknowstheIPaddressfortherequesteddomain.2.ItcancontactanotherDNSserverandtrytofind

theIPaddressforthenamerequested.Itmayhavetodothismultipletimes.Text3.Itcansay,"Idon'tknowtheIPaddressforthedomainyourequested,buthere'stheI

PaddressforaDNSserverthatknowsmorethanIdo."4.Itcanreturnanerrormessagebecausetherequesteddomainnameisinvali

dordoesnotexist.TextURLInternetprotocol,datatransmissionstandard:thestandardthatcontrolstheroutingand

structureofdatatransmittedovertheInternetInternetaddress:anaddressidentifyingthelocationofafileontheInternet,consistin

goftheprotocol,thecomputeronwhichthefileislocated,andthefile’slocationonthatcomputer.FullformUniformResourceLocatorKeyTermsIPQuestionsCanyou

listsometop-leveldomainnames?Whatdoes“www”standfor?.Whenyouusetheweb,whatdoestheDNSserversdoforyou?WhydoesDNSse

rverreturnanerrormessage?ExerciseTranslatethefollowingsentencesintoChineseWhenyouusetheWeborsendane-mailmessage,youuseadom

ainnametodoit.Withineverytop-leveldomainthereisahugelistofsecond-leveldomains.Everynameinthe.COMtop-

leveldomainmustbeunique.Theleft-mostword,likewww,isthehostname.Itspecifiesthenameofaspecificmachine(withaspecificIPaddress)

inadomain.ExerciseSimplewritingPleasedescribewhattheDNSserversdowhenusetheweb.Exercise——THANKYOU！——