Idokhumenti ye-DNS (ngezinye izikhathi ebizwa ngokuthi i-DNS resolver cache) yidatha yesikhashana, egcinwe uhlelo lokusebenza lwekhompiyutha, equkethe amarekhodi azo zonke izivakashi zokuvakasha kanye nokuzama ukuvakashela kumawebhusayithi nakwezinye izizinda ze-intanethi.
Ngamanye amazwi, i-DNS cache iyimemori ye-DNS lookups yamuva ukuthi ikhompyutha yakho ingasheshe ibhekisele lapho izama ukuthola indlela yokulayisha iwebhusayithi.
Iningi labantu lizwa kuphela inkulumo ethi "i-DNS cache" uma ibhekisela ekuhlanjuleni / ukuhlanza isilondolozi se-DNS ukuze kusize ukulungisa inkinga yokuxhumeka kwi-inthanethi. Kuningi kulokho ezansi kuleli khasi.
Inhloso ye-DNS Cache
I-inthanethi ixhomeke ku- Domain Name System (DNS) ukuze igcine uhlu lwazo zonke amawebhusayithi omphakathi kanye namakheli abo e- IP . Ungacabanga ngakho njengencwadi yefoni.
Ngencwadi yocingo, akudingeki ukuba ngekhanda inombolo yocingo wonke umuntu, yindlela kuphela yokuxhumana ngamafoni: ngenombolo. Ngendlela efanayo, i-DNS isetshenzisiwe ukuze sikwazi ukugwema ukubamba ngekhanda zonke ikheli le-IP lewebhusayithi, yindlela kuphela yokusebenzisa imishini yenethiwekhi yokuxhumana namawebhusayithi.
Lokhu kwenzeka ngemuva kwesihenqo uma ucela isiphequluli sakho sewebhu ukuthi ulayishe iwebhusayithi ...
Uthayipha ku-URL efana futhi isiphequluli sakho sewebhu sibuza i- router yakho ikheli le-IP. I-router inekheli le- DNS leseva elondolozwe, ngakho licela iseva ye-DNS ekhelini le-IP lalo gama lomkhosi . I-server ye-DNS ithola ikheli le-IP elingelakhe bese uyakwazi ukuqonda ukuthi iyiphi iwebhusayithi oyicelayo, emva kwalokho isiphequluli sakho singakwazi ukulayisha ikhasi elifanele.
Lokhu kwenzeka kuwo wonke amawebhusayithi ofuna ukuwavakashela. Njalo uma umsebenzisi evakashela iwebhusayithi ngegama lakhe lomsingisi, isiphequluli sewebhu siqala isicelo se-intanethi, kodwa lesi sicelo asikwazi ukuqedwa kuze kube yilapho igama lesayithi "liguqulwa" libe ikheli le-IP.
Inkinga yukuthi nakuba kunezinkulungwane zamaseva e-DNS omphakathi inethiwekhi yakho engayisebenzisa ukuzama ukusheshisa inqubo yokuguqulwa / isinqumo, kusengashesha ukuba nekhophi yendawo "yencwadi yocingo," lapho i-DNS caches ifika khona ukudlala.
Isilondolozi se-DNS sizama ukusheshisa inqubo ngokwengeziwe ngokusingatha isinqumo segama lamakheli avakashelwe kamuva ngaphambi kokuba isicelo sithunyelwe ku-intanethi.
Qaphela: Kukhona empeleni ama-caches e-DNS kuwo wonke ama-hierarchy yenqubo yokulanda "ekugcineni athola ikhompyutha yakho ukulayisha iwebhusayithi. Ikhompiyutha ifinyelela ku-router yakho, exhumana ne- ISP yakho, engase ifinyelele enye i-ISP ngaphambi kokuphelela kulokho okubizwa ngokuthi "amaseva we-DNS wezimpande." Ngamunye walawo maphuzu kuleyo nqubo unesilondolozi se-DNS ngesizathu esifanayo, okuzosheshisa inqubo yokuxazulula igama.
Yeka ukuthi i-DNS Cache isebenza kanjani
Ngaphambi kokuba isiphequluli siphakamise izicelo zayo kwinethiwekhi yangaphandle, ikhompiyutha ikhuluma ngayinye futhi ibheka igama lesizinda ku-database ye-DNS cache. I-database iqukethe uhlu lwawo wonke amagama esizinda esanda kutholakala kanye namakheli e-DNS abalwa ngabo okokuqala isicelo senziwe.
Okuqukethwe kwedokhumenti ye-DNS yendawo kungabonwa ku-Windows usebenzisa umyalo ipconfig / displaydns, nemiphumela efana nalokhu:
docs.google.com
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Igama lokurekhoda. . . . . : docs.google.com
Uhlobo lokurekhoda. . . . . : 1
Isikhathi Sokuphila. . . . : 21
Ubude beDatha. . . . . : 4
Ingxenye . . . . . . . : Impendulo
A (Host) Rekhoda. . . : 172.217.6.174
Ku-DNS, irekhodi "A" liyingxenye yokungena kwe-DNS equkethe ikheli le-IP legama elinikiwe. Idokhumenti ye-DNS igcina leli kheli, igama lewebhu eliceliwe, neminye imingcele eminye evela kokungenwa kwe-DNS.
Kuyini i-DNS I-Cache Poisoning?
I-DNS cache iba inongo noma ingcolile uma amagama wesizinda angagunyaziwe noma amakheli e-IP efakwa kuwo.
Ngezinye izikhathi isilondolozi singase sonakaliswe ngenxa yezingcweti zobuchwepheshe noma izingozi zokuphatha, kodwa ukubulawa kwesibindi se-DNS kuvame ukuhambisana namagciwane wekhompiyutha noma ukuhlaselwa kwenethiwekhi okufaka ukungena okungavumelekile kwe-DNS ku-cache.
Ubuhlungu buyabangela izicelo zamakhasimende ukuthi ziqondiswe ezindaweni ezingalungile, ngokuvamile amawebhusayithi angahle noma amakhasi agcwele izikhangiso.
Isibonelo, uma irekhodi le-docs.google.com elivela phezulu linerekhodi ehlukile "A", bese ufaka i-docs.google.com kusiphequluli sakho sewebhu, uzothathwa kwenye indawo.
Lokhu kubangela inkinga enkulu kumawebhusayithi adumile. Uma umhlaseli eqondisa isicelo sakho se-Gmail.com , isibonelo, kwiwebhusayithi ebukeka njenge-Gmail kodwa ayikho, ungase ugcine ukuhlupheka ngokuhlaselwa kobugebengu obunobungozi obufana ne- whaling .
DNS Ukuqhuma: Lokho Okushoyo Nendlela Yokukwenza
Uma ukuxazulula izinhlayiya zokugcina isikhashana noma ezinye izinkinga zokuxhumeka kwi-intanethi, umphathi wekhompuyutha angase afise ukususa (okucacile, ukusetha kabusha noma ukusula) i-cache cache.
Njengoba ukususa i-DNS cache kususa konke okufakwayo, kususa amarekhodi angavumelekile futhi kuphoqa ikhompyutha yakho ukuba iphinde ikhiphe lawo amakheli ngesikhathi esizayo uzama ukufinyelela lawo mawebhusayithi. Lawa amakheli amasha athathwa ku-server ye-DNS inethiwekhi yakho isethaphu ukusebenzisa.
Ngakho-ke, ukusebenzisa isibonelo ngenhla, uma irekhodi le-Gmail.com linobuthi futhi liqondisa kabusha kuwebhusayithi engaqondakali, ukususa i-DNS kuyisinyathelo esihle sokuqala ukuthola i-Gmail.com evamile.
Ku-Microsoft Windows, ungakwazi ukususa isilondolozi seDNS sendawo usebenzisa umyalo we- ipconfig / flushdns ku- Command Prompt . Uyazi ukuthi kusebenza uma ubona ukucushwa kwe- Windows IP ngokuphumelelayo kufakwe i-DNS Resolver Cache noma Iphumelele ngokuphumelelayo umlayezo we-DNS Resolver Cache .
Ngokusebenzisa ukuphela komyalo, abasebenzisi be-MacOS kufanele basebenzise i- dscacheutil -flushcache , kodwa bayazi ukuthi akukho "umyalezo" ophumelelayo ngemuva kokuthi ugijima, ngakho-ke awutsheli ukuthi ngabe kusebenza yini. Abasebenzisi be-Linux kufanele bafake umyalo wokuqalisa kabusha we /etc/rc.d/init.d/nscd .
I-router ingaba nesilondolozi se-DNS futhi, yingakho ukuvuselela i-router ngokuvamile kuyisinyathelo sokuxazulula izinkinga. Ngesizathu esifanayo ungase uhlwithe isilondolozi se-DNS kwikhompyutha yakho, ungaqalisa kabusha umzila wakho ukuze ususe okufakiwe kwe-DNS okugcinwe kwimemori yayo yesikhashana.