Yakaderera DNS latency kiyi yekumhanyisa internet kubhurawuza. Kuti udzikise, zvakakosha kunyatsosarudza DNS maseva uye . Asi danho rekutanga nderekubvisa mibvunzo isina basa.
Ichi ndicho chikonzero DNS yakatanga kugadzirwa seyakanyanya cacheable protocol. Vatariri venzvimbo vanoisa nguva yekurarama (TTL) yezvinyorwa zvega, uye vanogadzirisa vanoshandisa ruzivo urwu pavanochengeta zvinyorwa mundangariro kudzivirira traffic isingakoshi.
Ko caching inoshanda here? Makore akati kuti apfuura, tsvakiridzo yangu shoma yakaratidza kuti yakanga isina kukwana. Ngatitarisei mamiriro akaita zvinhu.
Kuti ndiunganidze ruzivo ndakaruka kuchengetedza kukosha kweTTL kwemhinduro. Inotsanangurwa seyakaderera TTL yemarekodhi ayo ega ega chikumbiro chinouya. Izvi zvinopa tarisiro yakanaka yekugovera kweTTL kwetraffic chaiyo, uye zvakare inofunga nezvekuzivikanwa kwezvikumbiro zvega. Iyo yakavharwa shanduro yeserver yakashanda kwemaawa akati wandei.
Iyo inoguma data set ine 1 marekodhi (zita, qtype, TTL, timestamp). Heino kugoverwa kweTTL kwese (X-axis iri TTL mumasekonzi):
Kunze kubva padiki bump pa86 (kunyanya kune maSOA marekodhi), zviri pachena kuti maTTL ari pazasi. Ngatitarisei zvakanyanya:
Zvakanaka, maTTL anopfuura awa haana kukosha. Zvadaro ngatitarisei pane huwandu 1β0:
Mazhinji maTTL anobva ku0 kusvika kumaminitsi gumi nemashanu:
Huzhinji hunobva pa0 kusvika ku5 maminetsi:
Hazvina kunyanya kunaka.
Cumulative kugovera kunoita kuti dambudziko rive pachena:
Hafu yemhinduro dzeDNS ine TTL yeminiti imwe kana isingasviki, uye zvikamu zvitatu zvine TTL yemaminetsi mashanu kana pasi.
Asi chimbomira, zvatonyanya kuipa. Mushure mezvose, iyi iTTL kubva kumaseva ane chiremera. Nekudaro, vatengi vanogadzirisa (semuenzaniso marouters, macache emunharaunda) vanogashira TTL kubva kumusoro uko kunogadzirisa, uye inoderera sekondi yega yega.
Saka mutengi anogona chaizvo kushandisa imwe neimwe yekupinda, paavhareji, hafu yepakutanga TTL asati atumira chikumbiro chitsva.
Zvichida aya akaderera maTTL anongoshanda kune zvisingawanzo zvikumbiro uye kwete akakurumbira mawebhusaiti uye maAPI? Ngatitarisei:
Iyo X axis iTTL, iyo Y axis ndeyekubvunza mukurumbira.
Nehurombo, iyo inonyanya kufarirwa mibvunzo ndiyo zvakare yakaipisisa ku cache.
Ngatiswededze pedyo:
Mutongo: zvakaipa chaizvo. Zvakanga zvatoipa kare, asi zvakatowedzera. DNS caching yave isingaite. Sezvo vanhu vashoma vanoshandisa yavo ISP's DNS solver (nezvikonzero zvakanaka), kuwedzera kwekunonoka kunowedzera kuoneka.
DNS caching yave yakakosha kune zvemukati chete zvisingashanyirwe nemunhu.
Ndokumbirawo muone kuti software inogona kududzira maTTL akaderera.
Nei zvakadaro
Sei marekodhi eDNS akaiswa kune yakaderera kudaro TTL?
- Legacy load balancers yakasara ine default settings.
- Pane ngano dzekuti DNS load balancing inoenderana neTTL (ichi hachisi chokwadi - kubvira mazuva eNetscape Navigator, vatengi vakasarudza imwe kero yeIP kubva kune seti yeRRs uye vakaedza imwe pachena kana vasingakwanise kubatana)
- Vatungamiri vanoda kuisa shanduko nekukasika, saka zviri nyore kuronga.
- Mutariri weDNS server kana loader balancer anoona basa rake sekushandisa zvakanaka gadziriro inokumbirwa nevashandisi, uye kwete kukurumidzira masaiti nemasevhisi.
- Low TTLs inokupa rugare rwepfungwa.
- Vanhu pakutanga vakaisa maTTL akaderera ekuyedza vobva vakanganwa kuvachinja.
Ini handina kubatanidza "akakundikana" mune iyo rondedzero nekuti iri kuramba ichiderera. Kana iwe uchida kudzosera vashandisi kune imwe network kuti ungoratidza peji yekukanganisa kana zvese zvimwe zvese zvaputswa, kunonoka kweinopfuura miniti 1 kunogamuchirwa.
Pamusoro pezvo, TTL yeminiti imwe inoreva kuti kana ane mvumo DNS maseva akavharirwa kweinopfuura miniti imwe, hapana mumwe munhu achakwanisa kuwana masevhisi anotsamira. Uye redundancy haizobatsiri kana chikonzero chiri chikanganiso chekugadzirisa kana hack. Kune rimwe divi, nemaTTL anonzwisisika, vatengi vazhinji vacharamba vachishandisa iyo yapfuura gadziriso uye havambo cherechedza chero chinhu.
Masevhisi eCDN uye mabharanzi emutoro ndiwo anonyanya kukonzeresa maTTL akaderera, kunyanya kana achibatanidza maCNAME ane akaderera maTTL uye marekodhi ane akaenzana akaderera (asi akazvimiririra) maTTL:
$ drill raw.githubusercontent.com raw.githubusercontent.com. 9 IN CNAME github.map.fastly.net. github.map.fastly.net. 20 IN A 151.101.128.133 github.map.fastly.net. 20 IN A 151.101.192.133 github.map.fastly.net. 20 IN A 151.101.0.133 github.map.fastly.net. 20 IN A 151.101.64.133
Pese panopera CNAME kana chero marekodhi eA, chikumbiro chitsva chinofanira kutumirwa. Vese vane 30 yechipiri TTL, asi haina kufanana. Iyo chaiyo avhareji TTL ichave 15 masekondi.
Asi chimbomira! Zvakatoipa. Vamwe vanogadzirisa vanozvibata zvakanyanya mune ino mamiriro ane maviri akabatana akaderera TTLs:
$ drill raw.githubusercontent.com @4.2.2.2 raw.githubusercontent.com. 1 IN CNAME github.map.fastly.net. github.map.fastly.net. 1 IN A 151.101.16.133
Iyo Level3 inogadzirisa pamwe inomhanya paBIND. Kana ukaramba uchitumira chikumbiro ichi, TTL ye1 inogara ichidzoserwa. raw.githubusercontent.com haina kumbovharwa.
Heino mumwe muenzaniso wemamiriro ezvinhu akadaro ane anonyanya kufarirwa domain:
$ drill detectportal.firefox.com @1.1.1.1 detectportal.firefox.com. 25 IN CNAME detectportal.prod.mozaws.net. detectportal.prod.mozaws.net. 26 IN CNAME detectportal.firefox.com-v2.edgesuite.net. detectportal.firefox.com-v2.edgesuite.net. 10668 IN CNAME a1089.dscd.akamai.net. a1089.dscd.akamai.net. 10 IN A 104.123.50.106 a1089.dscd.akamai.net. 10 IN A 104.123.50.88
Anenge matatu CNAME marekodhi. Ay. Imwe ine TTL yakanaka, asi haina basa zvachose. Mamwe maCNAME ane yekutanga TTL yemasekonzi makumi matanhatu, asi yemadomasi akamai.net iyo yakanyanya TTL masekonzi makumi maviri uye hapana kana imwe yadzo iri muchikamu.
Zvakadini nemadomasi anogara achitsvaga Apple zvishandiso?
$ drill 1-courier.push.apple.com @4.2.2.2 1-courier.push.apple.com. 1253 IN CNAME 1.courier-push-apple.com.akadns.net. 1.courier-push-apple.com.akadns.net. 1 IN CNAME gb-courier-4.push-apple.com.akadns.net. gb-courier-4.push-apple.com.akadns.net. 1 IN A 17.57.146.84 gb-courier-4.push-apple.com.akadns.net. 1 IN A 17.57.146.85
Dambudziko rakafanana neFirefox neTTL richange rakanamira pasekondi imwe nguva zhinji kana uchishandisa Level1 solver.
Dropbox?
$ drill client.dropbox.com @8.8.8.8 client.dropbox.com. 7 IN CNAME client.dropbox-dns.com. client.dropbox-dns.com. 59 IN A 162.125.67.3 $ drill client.dropbox.com @4.2.2.2 client.dropbox.com. 1 IN CNAME client.dropbox-dns.com. client.dropbox-dns.com. 1 IN A 162.125.64.3
Pakurekodha safebrowsing.googleapis.com Kukosha kweTTL masekonzi makumi matanhatu, senge Facebook domains. Uye, zvakare, kubva pakuona kwemutengi, aya maitiro akaiswa nepakati.
Zvakadini nekuisa shoma TTL?
Ndichishandisa zita, rudzi rwekukumbira, TTL, uye chitambi chenguva chakachengetwa, ndakanyora script kutevedzera miriyoni 1,5 zvikumbiro zvichipfuura nemugadziri we caching kufungidzira huwandu hwezvikumbiro zvisingakoshi zvakatumirwa nekuda kwekupinda cache kwapera.
47,4% yezvikumbiro zvakaitwa mushure mekunge rekodhi iripo yapera. Izvi zvakakwirira zvisina musoro.
Chii chichava mhedzisiro pane caching kana iyo shoma TTL yakaiswa?
Iyo X axis ndiyo shoma TTL kukosha. Marekodhi ane tsime TTLs pamusoro pehukoshi uhwu haabatike.
Iyo Y axis iperesenti yezvikumbiro kubva kune mutengi atova necached yekupinda, asi yapera uye iri kuita chikumbiro chitsva.
Chikamu chezvikumbiro "zvekuwedzera" chinodzikiswa kubva pa47% kusvika pa36% nekungoisa shoma TTL kusvika kumaminitsi mashanu. Nekuisa iyo shoma TTL kusvika kumaminitsi gumi nemashanu, nhamba yezvikumbiro izvi inodonha kusvika 5%. TTL shoma yeawa imwe inodzikisira kusvika 15%. Musiyano unokosha!
Zvakadini nekusachinja chero chinhu padivi pesevha, asi pachinzvimbo chekuisa iyo shoma TTL mune mutengi DNS cache (marouter, emuno resolutions)?
Huwandu hwezvikumbiro zvinodiwa hunodonha kubva pa47% kusvika pa34% neTTL shoma yemaminetsi mashanu, kusvika pa5% ine maminetsi mashoma gumi nemashanu, uye kusvika 25% neawa isingasviki 15. Zvichida maminetsi makumi mana ndiwo akanakisa.
Kukanganisa kwekuchinja kudiki uku kwakakura.
Migumisiro yacho ndeipi?
Ehe, sevhisi inogona kutamirwa kune mutsva wegore mupi, sevha nyowani, network nyowani, inoda kuti vatengi vashandise marekodhi ezvino DNS. Uye diki TTL inobatsira kuita shanduko yakadaro mushe uye zvisingaoneki. Asi neshanduko yezvivakwa zvitsva, hapana anotarisira kuti vatengi vatamire kune marekodhi matsva eDNS mukati meminiti 1, maminetsi mashanu, kana maminetsi gumi nemashanu. Kuisa iyo shoma TTL kusvika 5 maminetsi panzvimbo ye15 maminetsi hazvitadzise vashandisi kuwana sevhisi.
Nekudaro, izvi zvichaderedza zvakanyanya latency uye kuvandudza kuvanzika uye kuvimbika nekudzivisa zvikumbiro zvisingakoshi.
Ehe, maRFC anoti TTL inofanira kunyatsoteverwa. Asi chokwadi ndechekuti iyo DNS system yanyanya kusashanda.
Kana uri kushanda nemaseva ane chiremera eDNS, ndapota tarisa maTTL ako. Unoda chaizvoizvo tsika dzakaderera zvakadaro zvinosekesa here?
Ehe, pane zvikonzero zvakanaka zvekuseta maTTL madiki eDNS marekodhi. Asi kwete ye75% yeDNS traffic inoramba isina kushanduka.
Uye kana nekuda kwechimwe chikonzero iwe unofanirwa chaizvo kushandisa yakaderera TTLs yeDNS, panguva imwechete ita shuwa kuti yako saiti haina caching yakagoneswa. Nezvikonzero zvimwe chetezvo.
Kana iwe uine yemuno DNS cache inomhanya, senge iyo inokutendera iwe kuseta mashoma TTLs, shandisa basa iri. Izvi zvakanaka. Hapana chakaipa chichaitika. Isa iyo shoma TTL kune angangoita maminetsi makumi mana (40 masekonzi) uye 2400 awa. Mutsara unonzwisisika.
Source: www.habr.com