Ib qho DNS cache (qee zaus hu ua DNS resolver cache) yog ib qhov chaw khaws ntaub ntawv ib ntus, tswj los ntawm lub computer qhov operating system, uas muaj cov ntaub ntawv ntawm tag nrho cov kev mus xyuas tas thiab sim mus xyuas cov websites thiab lwm yam hauv internet.
Hauv, ib qho DNS cache tsuas yog nco txog cov kev tshawb xyuas DNS tsis ntev los no uas koj lub computer tuaj yeem ceev nrooj xa mus thaum nws tseem tabtom los xyuas seb yuav ua li cas mus thauj ib lub website.
Cov neeg feem coob tsuas hnov cov kab lus "DNS cache" thaum nws hais txog kev ywj pheej / cais cov kab xev xev kom tau kev txhim kho cov teeb meem hauv internet. Muaj ntau ntxiv rau hauv qab ntawm nplooj ntawv no.
Lub Ntsiab Ntawm Daim Ntawv Cache
Hauv internet vam khom rau ntawm Qhov Chaw Npe Lub Npe (DNS) kom muaj kev lagluam rau tag nrho cov pejxeem cov websites thiab lawv cov IP chaw nyob . Koj tuaj yeem xav txog nws zoo li phau ntawv xov tooj.
Nrog rau ib phau ntawv xov tooj, peb tsis tas yuav cim txhua tus xov tooj tus xov tooj, uas yog tib txoj kev sib txuas lus xov tooj: nrog ib tug xov tooj. Nyob rau hauv tib txoj kev, DNS yog siv li ntawd peb yuav zam tsis tau nrog txhua lub website qhov chaw tus IP, uas yog tib txoj kev ntawm cov khoom siv sib txuas lus nrog cov websites.
Qhov no yog dab tsi tshwm sim tom qab tus txheej txheem thaum koj nug koj qhov web browser mus thauj ib lub website ...
Koj ntaus ntawv hauv qhov URL zoo li thiab koj qhov web browser nug koj tus router rau IP chaw nyob. Tus router muaj DNS server chaw nyob, ces nws nug tus DNS neeg rau zaub mov rau qhov chaw tus IP ntawm ntawd hostname . DNS neeg pom tus IP chaw nyob uas belongs rau thiab tom qab ntawd nws muaj peev xwm nkag siab txog lub website koj tau thov rau, tom qab uas koj tus browser tau ces muab nplooj ntawv tsim nyog.
Qhov no tshwm sim rau txhua lub website uas koj xav mus xyuas. Txhua zaus uas tus neeg tuaj yeem tuaj xyuas lub website ntawm nws lub npe, lub web browser pib thov hauv internet, tab sis qhov kev thov no tuaj yeem tsis ua tiav kom txog rau thaum lub npe ntawd yog "hloov dua siab tshiab" rau hauv IP chaw nyob.
Qhov teeb meem yog tias txawm tias muaj tons ntawm cov pej xeem siv DNS servers hauv koj lub network siv los sim ua qhov kev hloov ua ke / txheej txheem, nws tseem cuam tshuam kom muaj ib daim ntawv luam ntawm cov ntawv xov tooj, uas yog qhov uas yog qhov caches DNS ua si.
Cov ntaub ntawv teev npe DNS cache coj los txhim kho cov txheej txheem ntau dua los ntawm kev tuav lub npe daws teeb meem ntawm cov chaw nyuam qhuav mus xyuas ua ntej thov xa tawm mus rau hauv internet.
Ceebtoom: Muaj cov kabmob hauv DNS ntawm txhua hierarchy ntawm txoj kev "lookup" uas thaum kawg tau txais koj lub computer mus thauj lub website. Lub computer nce mus txog koj lub router, uas tiv tauj koj ISP , uas tej zaum yuav ntaus lwm ISP ua ntej xaus ntawm qhov kev hu ua "root DNS servers." Txhua ntawm cov ntsiab lus hauv cov txheej txheem muaj DNS cache rau tib qho laj thawj, uas yog los mus ceev cov txheej txheem daws teeb meem.
Cas ib DNS Cache Ua Haujlwm
Ua ntej qhib qhov browser nws qhov kev thov mus rau sab nraud network, lub computer intercepts txhua tus thiab saib txog lub npe no hauv DNS cache database. Lub database muaj ib daim ntawv teev tag nrho cov nyuam qhuav nkag mus siv cov npe thiab cov chaw nyob uas DNS them rau lawv thawj zaug tau thov.
Tus txheem ntawm ib lub zos DNS cache tuaj yeem raug saib xyuas ntawm lub qhov rais siv qhov kev txiav txim siab ipconfig / displaydns, nrog cov zoo xws li qhov no:
docs.google.com
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Sau Lub Npe. . . . . : docs.google.com
Sau Hom. . . . . : 1
Lub sij hawm nyob. . . . : 21
Cov ntaub ntawv Ntev. . . . . : 4
Seem. . . . . . . : Teb
Ib daim ntawv (Hwm). . . : 172.217.6.174
Hauv DNS, tus "A" cov ntaub ntawv yog ib feem ntawm qhov DNS nkag uas muaj qhov chaw nyob tus IP rau tus tswv tsev muab lub npe. Lub DNS cache stores no qhov chaw nyob, lub npe lub npe, thiab ntau lwm yam tsis los ntawm tus tswv tsev DNS nkag.
DNS Cache Poisoning yog dab tsi?
Ib qho DNS cache ua tshuaj lom los yog kuab thaum lub npe tso cai tsis tau tso cai los yog cov chaw nyob hauv IP raug tso rau hauv nws.
Qee zaus ib qho cache tej zaum yuav tawg vim muaj kev ua yuam kev los yog kev raug mob, tab sis DNS cache poisoning feem ntau yog cuam tshuam nrog cov kab mob computer los yog lwm cov kev tawm tsam network uas nkag tsis tau DNS nkag rau hauv cache.
Tshuaj lom neeg ua rau cov neeg thov tuaj yeem raug xa rov mus rau qhov chaw tsis ncaj ncees lawm, feem ntau yog cov websites phem lossis cov nplooj ntawv uas muaj cov ntawv tshaj tawm.
Piv txwv, yog tias docs.google.com cov ntaub ntawv sau tau los ntawm cov ntaub ntawv sib txawv, "A", ces thaum koj nkag mus docs.google.com hauv koj qhov web browser, koj yuav tsum muab lwm qhov chaw.
Qhov no yog qhov teeb meem loj heev rau cov websites nrov. Yog tias tus neeg tua neeg tau xa koj daim ntawv thov Gmail.com , piv txwv li, mus rau lub website uas zoo nkaus li Gmail, tiam sis tsis yog, koj yuav raug kev tsim txom los ntawm kev phom sij xws li kev nplhaib .
DNS Flushing: Nws Yuav Ua Li Cas Thiab Ua Li Cas?
Thaum teeb meem cache lom los yog lwm yam teeb meem hauv internet, ib tus thawj tswj hwm computer yuav xav tawm yaug (xws li meej, pib dua, los sis lwv) DNS cache.
Vim tias clearing lub DNS cache tshem tag nrho cov nkag, nws deletes txhua invalid cov ntaub ntawv dhau thiab yuam koj lub computer mus rau repopulate cov chaw nyob rau lwm zaus koj sim nkag cov websites. Cov chaw tshiab no yog muab los ntawm DNS neeg rau zaub mov koj lub network yog teeb siv.
Yog li, siv qhov piv txwv saum toj no, yog tias Gmail.com cov ntaub ntawv tau raug lom thiab rov redirecting koj mus rau lub website uas coj txawv txawv, ntws tawm ntawm DNS yog thawj kauj ruam zoo kom tau txais Gmail.com tsis tu ncua dua.
Hauv Microsoft lub Xeev, koj tuaj yeem yoov rau hauv DNS cache uas siv cov lus qhia ntawm ipconfig / flushdns hauv kev hais kom ua . Koj paub tias nws ua haujlwm thaum koj pom tus IP qhov kev txawb IP tau ntse dhau lub DNS Resolver Cache lossis Successfully flushed DNS Resolver Cache lus.
Los ntawm kev hais kom dav dav, cov neeg siv kev lag luam yuav tsum siv dscacheutil -flushcache , tab sis paub tias tsis muaj "lus" zoo tom qab nws sau, yog li koj tsis tau qhia yog tias nws ua haujlwm. Linux cov neeg siv yuav tsum tau nkag mus rau /etc/rc.d/init.d/nscd restart hais kom ua.
Ib lub router muaj peev xwm muaj ib qho DNS cache zoo li, uas yog vim li cas rebooting ib lub router yog feem ntau yog ib qho teeb meem kev daws teeb meem. Vim li cas koj thiaj yauv yoog lub DNS cache hauv koj lub computer, koj tuaj yeem reboot koj lub router kom tshem tau cov DNS nkag rau hauv nws qhov kev nco ib ntus.