{"id":52324,"date":"2019-11-06T00:00:00","date_gmt":"2019-11-05T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/hvatit-ispolzovat-smehotvorno-malyj-ttl-dlya-dns"},"modified":"2021-01-02T13:04:14","modified_gmt":"2021-01-02T11:04:14","slug":"hvatit-ispolzovat-smehotvorno-malyj-ttl-dlya-dns","status":"publish","type":"post","link":"https:\/\/prohoster.info\/it\/blog\/administrirovanie\/hvatit-ispolzovat-smehotvorno-malyj-ttl-dlya-dns","title":{"rendered":"Smettila di usare un TTL ridicolo per il DNS","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>Una bassa latenza DNS \u00e8 un fattore chiave per un funzionamento veloce su Internet. Per minimizzarla, \u00e8 fondamentale scegliere con attenzione i server DNS e <noindex><a rel=\"nofollow\" href=\"https:\/\/github.com\/DNSCrypt\/dnscrypt-resolvers\/blob\/master\/v2\/relays.md\">rilievi anonimi<\/a><\/noindex>. Ma prima di tutto, bisogna eliminare le query superflue.<\/p>\n<p>Per questo motivo, il DNS \u00e8 stato inizialmente progettato come un protocollo altamente cacheabile. Gli amministratori delle zone impostano il tempo di vita (TTL) per singoli record, e i resolver utilizzano queste informazioni per memorizzare i record nella cache, evitando cos\u00ec traffico non necessario.<\/p>\n<p>\u00c8 efficace la memorizzazione nella cache? Alcuni anni fa, una mia piccola ricerca ha mostrato che non \u00e8 perfetta. Diamo un'occhiata alla situazione attuale.<br \/>\n<noindex><a rel=\"nofollow\" name=\"habracut\"><\/a><\/noindex><br \/>\nPer raccogliere informazioni, ho patchato <noindex><a rel=\"nofollow\" href=\"https:\/\/github.com\/jedisct1\/encrypted-dns-server\">Encrypted DNS Server<\/a><\/noindex> per mantenere il valore TTL per la risposta. Esso \u00e8 definito come il TTL minimo dei suoi record per ogni richiesta in arrivo. Questo fornisce una buona panoramica della distribuzione del TTL nel traffico reale, oltre a considerare la popolarit\u00e0 di singole richieste. La versione patchata del server ha funzionato per alcune ore.<\/p>\n<p>\u0420\u0435\u0437\u0443\u043b\u044c\u0442\u0438\u0440\u0443\u044e\u0449\u0438\u0439 \u043d\u0430\u0431\u043e\u0440 \u0434\u0430\u043d\u043d\u044b\u0445 \u0441\u043e\u0441\u0442\u043e\u0438\u0442 \u0438\u0437 1&nbsp;583&nbsp;579 \u0437\u0430\u043f\u0438\u0441\u0435\u0439 (name, qtype, TTL, timestamp). \u0412\u043e\u0442 \u043e\u0431\u0449\u0435\u0435 \u0440\u0430\u0441\u043f\u0440\u0435\u0434\u0435\u043b\u0435\u043d\u0438\u0435 TTL (\u043e\u0441\u044c X \u2014 \u044d\u0442\u043e TTL \u0432 \u0441\u0435\u043a\u0443\u043d\u0434\u0430\u0445):<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/ce19a1ceb07e1fd2f3b2284f86271eac.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>\u0415\u0441\u043b\u0438 \u043d\u0435 \u0441\u0447\u0438\u0442\u0430\u0442\u044c \u043d\u0435\u0437\u043d\u0430\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e\u0433\u043e \u0431\u0443\u0433\u0440\u0430 \u043d\u0430 86&nbsp;400 (\u0432 \u043e\u0441\u043d\u043e\u0432\u043d\u043e\u043c, \u0434\u043b\u044f \u0437\u0430\u043f\u0438\u0441\u0435\u0439 SOA), \u0434\u043e\u0432\u043e\u043b\u044c\u043d\u043e \u043e\u0447\u0435\u0432\u0438\u0434\u043d\u043e, \u0447\u0442\u043e TTL \u043d\u0430\u0445\u043e\u0434\u044f\u0442\u0441\u044f \u0432 \u043d\u0438\u0437\u043a\u043e\u043c \u0434\u0438\u0430\u043f\u0430\u0437\u043e\u043d\u0435. \u041f\u043e\u0441\u043c\u043e\u0442\u0440\u0438\u043c \u0431\u043b\u0438\u0436\u0435:<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/abbe48952b616e1c5bdb18c2dc103dc7.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>Bene, i TTL superiori a 1 ora sono statisticamente poco significativi. Concentrandoci quindi sull'intervallo 0\u22123600:<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/f8a88267e1868a55d9234f66ad8c5dee.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>La maggior parte dei TTL \u00e8 compresa tra 0 e 15 minuti:<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/aab650c806097513a5924e5262211ea5.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>La stragrande maggioranza \u00e8 compresa tra 0 e 5 minuti:<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/736af4b33b745fb0d5070200fa511426.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>Questo non \u00e8 molto positivo.<\/p>\n<p>La distribuzione cumulativa rende il problema ancora pi\u00f9 evidente:<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/a3a4f03188dd6dbbf4558076b827f6a5.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>\u0412 \u043f\u043e\u043b\u043e\u0432\u0438\u043d\u0435 DNS-\u043e\u0442\u0432\u0435\u0442\u043e\u0432 TTL \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 1 \u043c\u0438\u043d\u0443\u0442\u0443 \u0438\u043b\u0438 \u043c\u0435\u043d\u044c\u0448\u0435, \u0430 \u0443 \u0442\u0440\u0451\u0445 \u0447\u0435\u0442\u0432\u0435\u0440\u0442\u0435\u0439&nbsp;\u2014 5 \u043c\u0438\u043d\u0443\u0442 \u0438\u043b\u0438 \u043c\u0435\u043d\u044c\u0448\u0435.<\/p>\n<p>Ma aspetta, in realt\u00e0 \u00e8 ancora peggio. Questi sono i TTL dai server autoritativi. Tuttavia, i risolutori client (ad esempio, router, cache locali) ricevono i TTL dai risolutori superiori, e questo si riduce ogni secondo.<\/p>\n<p>Dunque, il client pu\u00f2 effettivamente utilizzare ogni record, in media, per met\u00e0 del TTL originale, dopo di che invier\u00e0 una nuova richiesta.<\/p>\n<p>Forse questi TTL molto bassi riguardano solo richieste insolite e non siti web e API popolari? Vediamo:<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/2680f9669a90f449a593edcc84ca0dc8.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>\u041e\u0441\u044c X&nbsp;\u2014 \u044d\u0442\u043e TTL, \u043e\u0441\u044c Y&nbsp;\u2014 \u043f\u043e\u043f\u0443\u043b\u044f\u0440\u043d\u043e\u0441\u0442\u044c \u0437\u0430\u043f\u0440\u043e\u0441\u043e\u0432.<\/p>\n<p>Purtroppo, le richieste pi\u00f9 popolari sono anche le meno cachate.<\/p>\n<p>Avviciniamo:<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/c670382b195169779743f43fd7b15827.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>Verdetto: la situazione \u00e8 davvero grave. Era gi\u00e0 malmessa prima, ma ora \u00e8 anche peggio. La memorizzazione nella cache del DNS \u00e8 diventata praticamente inutile. Con sempre meno persone che utilizzano il resolver DNS del proprio provider (per buoni motivi), l'aumento della latenza \u00e8 diventato pi\u00f9 evidente.<\/p>\n<p>La memorizzazione nella cache del DNS \u00e8 utile solo per i contenuti che nessuno visita.<\/p>\n<p>Si noti inoltre che il software pu\u00f2 <noindex><a rel=\"nofollow\" href=\"https:\/\/00f.net\/2011\/11\/17\/how-long-does-a-dns-ttl-last\/\">interpretare diversamente<\/a><\/noindex> i bassi TTL.<\/p>\n<h1>Perch\u00e9?<\/h1>\n<p>Perch\u00e9 viene impostato un TTL cos\u00ec basso per le registrazioni DNS?<\/p>\n<ul>\n<li>I bilanciatori di carico obsoleti sono rimasti con le impostazioni di default.<\/li>\n<li>\u0425\u043e\u0434\u044f\u0442 \u043c\u0438\u0444\u044b, \u0447\u0442\u043e \u0431\u0430\u043b\u0430\u043d\u0441\u0438\u0440\u043e\u0432\u043a\u0430 \u043d\u0430\u0433\u0440\u0443\u0437\u043a\u0438 \u043f\u043e DNS \u0437\u0430\u0432\u0438\u0441\u0438\u0442 \u043e\u0442 TTL (\u044d\u0442\u043e \u043d\u0435 \u0442\u0430\u043a&nbsp;\u2014 \u0441\u043e \u0432\u0440\u0435\u043c\u0451\u043d Netscape Navigator \u043a\u043b\u0438\u0435\u043d\u0442\u044b \u0432\u044b\u0431\u0438\u0440\u0430\u044e\u0442 \u0441\u043b\u0443\u0447\u0430\u0439\u043d\u044b\u0439 IP-\u0430\u0434\u0440\u0435\u0441 \u0438\u0437 \u043d\u0430\u0431\u043e\u0440\u0430 RR \u0438 \u043f\u0440\u043e\u0437\u0440\u0430\u0447\u043d\u043e \u043f\u0440\u043e\u0431\u0443\u044e\u0442 \u0434\u0440\u0443\u0433\u043e\u0439, \u0435\u0441\u043b\u0438 \u043d\u0435 \u043c\u043e\u0433\u0443\u0442 \u043f\u043e\u0434\u043a\u043b\u044e\u0447\u0438\u0442\u044c\u0441\u044f)<\/li>\n<li>Gli amministratori desiderano applicare le modifiche immediatamente, perch\u00e9 \u00e8 pi\u00f9 facile pianificare in questo modo.<\/li>\n<li>L'amministratore del server DNS o del bilanciamento del carico ha il compito di implementare in modo efficiente la configurazione richiesta dagli utenti, piuttosto che accelerare il funzionamento dei siti e servizi.<\/li>\n<li>Bassi TTL offrono tranquillit\u00e0.<\/li>\n<li>Le persone inizialmente impostano bassi TTL per i test e poi dimenticano di modificarli.<\/li>\n<\/ul>\n<p>Non ho incluso nella lista il 'failover' perch\u00e9 sta diventando sempre meno rilevante. Se \u00e8 necessario reindirizzare gli utenti a un'altra rete solo per visualizzare una pagina di errore quando tutto il resto \u00e8 andato in crash, probabilmente \u00e8 accettabile un ritardo superiore a un minuto.<\/p>\n<p>Inoltre, un TTL di un minuto significa che se i server DNS autorevoli vengono bloccati per pi\u00f9 di un minuto, nessun altro potr\u00e0 accedere ai servizi dipendenti. E la ridondanza non aiuter\u00e0 se la causa \u00e8 un errore di configurazione o un attacco. D'altra parte, con TTL ragionevoli, molti clienti continueranno a utilizzare la configurazione precedente senza accorgersene.<\/p>\n<p>Nei TTL bassi sono in gran parte colpevoli i servizi CDN e i bilanciatori di carico, specialmente quando combinano CNAME con TTL piccoli e record con altri piccoli (ma indipendenti) TTL:<\/p>\n<pre>$ drill raw.githubusercontent.com\nraw.githubusercontent.com.\t9\tIN\tCNAME\tgithub.map.fastly.net.\ngithub.map.fastly.net.\t20\tIN\tA\t151.101.128.133\ngithub.map.fastly.net.\t20\tIN\tA\t151.101.192.133\ngithub.map.fastly.net.\t20\tIN\tA\t151.101.0.133\ngithub.map.fastly.net.\t20\tIN\tA\t151.101.64.133<\/pre>\n<p>Ogni volta che scade un CNAME o uno qualsiasi dei record A, \u00e8 necessario inviare una nuova richiesta. Entrambi hanno un TTL di 30 secondi, ma non coincidono. Il reale TTL medio sar\u00e0 di 15 secondi.<\/p>\n<p>Ma aspetta! \u00c8 ancora peggio. Alcuni resolver si comportano molto male in una situazione con due TTL bassi collegati:<\/p>\n<pre>$ drill raw.githubusercontent.com @4.2.2.2\nraw.githubusercontent.com.\t1\tIN\tCNAME\tgithub.map.fastly.net.\ngithub.map.fastly.net.\t1\tIN\tA\t151.101.16.133<\/pre>\n<p>Il resolver Level3 probabilmente funziona su BIND. Se continui a inviare questa richiesta, verr\u00e0 sempre restituito un TTL pari a 1. Fondamentalmente, <code>raw.githubusercontent.com<\/code> non viene mai memorizzato nella cache.<\/p>\n<p>Ecco un altro esempio di questa situazione con un dominio molto popolare:<\/p>\n<pre>$ drill detectportal.firefox.com @1.1.1.1\ndetectportal.firefox.com.\t25\tIN\tCNAME\tdetectportal.prod.mozaws.net.\ndetectportal.prod.mozaws.net.\t26\tIN\tCNAME\tdetectportal.firefox.com-v2.edgesuite.net.\ndetectportal.firefox.com-v2.edgesuite.net.\t10668\tIN\tCNAME\ta1089.dscd.akamai.net.\na1089.dscd.akamai.net.\t10\tIN\tA\t104.123.50.106\na1089.dscd.akamai.net.\t10\tIN\tA\t104.123.50.88<\/pre>\n<p>Almeno tre record CNAME. Ai. Uno ha un TTL decente, ma \u00e8 completamente inutile. Negli altri CNAME, il TTL iniziale \u00e8 di 60 secondi, ma per i domini <code>akamai.net<\/code> il TTL massimo \u00e8 di 20 secondi e nessuno di essi \u00e8 in fase.<\/p>\n<p>E per i domini che interrogano costantemente i dispositivi Apple?<\/p>\n<pre>$ drill 1-courier.push.apple.com @4.2.2.2\n1-courier.push.apple.com.\t1253\tIN\tCNAME\t1.courier-push-apple.com.akadns.net.\n1.courier-push-apple.com.akadns.net.\t1\tIN\tCNAME\tgb-courier-4.push-apple.com.akadns.net.\ngb-courier-4.push-apple.com.akadns.net.\t1\tIN\tA\t17.57.146.84\ngb-courier-4.push-apple.com.akadns.net.\t1\tIN\tA\t17.57.146.85<\/pre>\n<p>Lo stesso problema di Firefox, e il TTL rimarr\u00e0 gran parte del tempo a 1 secondo utilizzando il resolver Level3.<\/p>\n<p>Dropbox?<\/p>\n<pre>$ drill client.dropbox.com @8.8.8.8\nclient.dropbox.com.\t7\tIN\tCNAME\tclient.dropbox-dns.com.\nclient.dropbox-dns.com.\t59\tIN\tA\t162.125.67.3\n\n$ drill client.dropbox.com @4.2.2.2\nclient.dropbox.com.\t1\tIN\tCNAME\tclient.dropbox-dns.com.\nclient.dropbox-dns.com.\t1\tIN\tA\t162.125.64.3<\/pre>\n<p>Per il record <code>safebrowsing.googleapis.com<\/code> il valore TTL \u00e8 di 60 secondi, proprio come per i domini di Facebook. E, ancora una volta, dal punto di vista del cliente, questi valori si dimezzano.<\/p>\n<h1>Che ne dici di impostare un TTL minimo?<\/h1>\n<p>Utilizzando il nome, il tipo di richiesta, il TTL e il timestamp inizialmente salvato, ho scritto uno script per simulare 1,5 milioni di richieste che passano attraverso un risolutore cache, per valutare il volume di richieste superflue inviate a causa di una registrazione di cache scaduta.<\/p>\n<p>Il 47,4% delle richieste sono state effettuate dopo la scadenza della registrazione esistente. Questo \u00e8 un dato ingiustificatamente alto.<\/p>\n<p>Quale sar\u00e0 l'impatto sulla memorizzazione nella cache se viene impostato un TTL minimo?<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/3abd417d312450519b45f66865b23763.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>L'asse X rappresenta i valori minimi di TTL. Le registrazioni con TTL iniziali superiori a questo valore non sono interessate.<\/p>\n<p>L'asse Y rappresenta la percentuale delle richieste provenienti da un client che ha gi\u00e0 una registrazione cache, ma la cui validit\u00e0 \u00e8 scaduta e quindi effettua una nuova richiesta.<\/p>\n<p>La quota di richieste \"superflue\" diminuisce dal 47% al 36% semplicemente impostando un TTL minimo di 5 minuti. Impostando un TTL minimo di 15 minuti, il numero di queste richieste scende al 29%. Un TTL minimo di un'ora riduce ulteriormente il numero a 17%. Una differenza significativa!<\/p>\n<p>Che ne dite di non apportare alcuna modifica lato server e invece impostare dei TTL minimi nei cache DNS dei client (router, risolutori locali)?<\/p>\n<p><img decoding=\"async\" alt=\"Smettila di usare un TTL ridicolo per il DNS\" src=\"\/wp-content\/uploads\/2019\/11\/107a2bd53797d421d65ac7260bf78dfe.jpg\" style=\"display:block;margin: 0 auto;\"><\/p>\n<p>Il numero di richieste necessarie diminuisce dal 47% al 34% quando si imposta un TTL minimo di 5 minuti, al 25% con un minimo di 15 minuti e al 13% con un minimo di 1 ora. Il valore ottimale potrebbe essere di 40 minuti.<\/p>\n<p>L'impatto di questa piccola modifica \u00e8 enorme.<\/p>\n<h1>Quali sono le conseguenze?<\/h1>\n<p>Certo, il servizio pu\u00f2 essere trasferito a un nuovo fornitore di cloud, a un nuovo server, a una nuova rete, richiedendo ai clienti di utilizzare i record DNS pi\u00f9 recenti. Un TTL sufficientemente basso facilita una transizione fluida e impercettibile. Tuttavia, con il passaggio a una nuova infrastruttura, nessuno si aspetta che i clienti aggiornino i loro record DNS in 1 minuto, 5 minuti o 15 minuti. Impostare un tempo di vita minimo di 40 minuti invece di 5 minuti non impedir\u00e0 agli utenti di accedere al servizio.<\/p>\n<p>Tuttavia, ci\u00f2 consentir\u00e0 di ridurre significativamente la latenza e aumentare la riservatezza e l'affidabilit\u00e0, evitando richieste inutili.<\/p>\n<p>Certo, le RFC dicono che bisogna rispettare rigorosamente il TTL. Ma la realt\u00e0 \u00e8 che il sistema DNS \u00e8 diventato troppo inefficiente.<\/p>\n<p>Se stai lavorando con server DNS autoritativi, controlla i tuoi TTL. Hai davvero bisogno di valori cos\u00ec ridicolmente bassi?<\/p>\n<p>Certo, ci sono buone ragioni per impostare TTL bassi per i record DNS. Ma non per il 75% del traffico DNS, che praticamente non cambia.<\/p>\n<p>E se per qualche motivo hai realmente bisogno di utilizzare TTL bassi per il DNS, assicurati che la cache sul tuo sito non sia abilitata. Per le stesse ragioni.<\/p>\n<p>Se hai una cache DNS locale in funzione, come <noindex><a rel=\"nofollow\" href=\"https:\/\/github.com\/dnscrypt\/dnscrypt-proxy\">dnscrypt-proxy<\/a><\/noindex>, che consente di impostare TTL minimi, utilizza questa funzione. Va bene. Non succeder\u00e0 nulla di male. Imposta un TTL minimo tra 40 minuti (2400 secondi) e 1 ora. Un intervallo del tutto ragionevole.<\/p>\n<p>Fonte: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/habr.com\/ru\/post\/474450\/\">habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u041d\u0438\u0437\u043a\u0430\u044f \u0437\u0430\u0434\u0435\u0440\u0436\u043a\u0430 DNS \u2014 \u043a\u043b\u044e\u0447\u0435\u0432\u043e\u0439 \u0444\u0430\u043a\u0442\u043e\u0440 \u0434\u043b\u044f \u0431\u044b\u0441\u0442\u0440\u043e\u0439 \u0440\u0430\u0431\u043e\u0442\u044b \u0432 \u0438\u043d\u0442\u0435\u0440\u043d\u0435\u0442\u0435. \u0427\u0442\u043e\u0431\u044b \u0435\u0451 \u043c\u0438\u043d\u0438\u043c\u0438\u0437\u0438\u0440\u043e\u0432\u0430\u0442\u044c, \u0432\u0430\u0436\u043d\u043e \u0442\u0449\u0430\u0442\u0435\u043b\u044c\u043d\u043e \u043f\u043e\u0434\u043e\u0431\u0440\u0430\u0442\u044c DNS-\u0441\u0435\u0440\u0432\u0435\u0440\u044b \u0438 \u0430\u043d\u043e\u043d\u0438\u043c\u043d\u044b\u0435 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\/>\n\t\t<meta property=\"article:published_time\" content=\"2019-11-05T21:00:00+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2021-01-02T11:04:14+00:00\" \/>\n\t\t<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/prohoster\" \/>\n\t\t<meta property=\"article:author\" content=\"https:\/\/www.facebook.com\/prohoster\" \/>\n\t\t<!-- All in One SEO -->\n\n","aioseo_head_json":{"title":"\ud83e\udd47Basta utilizzare un TTL ridicolmente basso per il DNS | ProHoster","description":"Una bassa latenza DNS \u00e8 un fattore chiave per una navigazione veloce su internet. Per minimizzarla, \u00e8 importante scegliere attentamente i server DNS e i relay anonimi. Tuttavia, la prima cosa da fare \u00e8 eliminare le query inutili. \u00c8 per questo che il DNS \u00e8 stato progettato fin dall'inizio come un protocollo altamente cacheabile. Gli amministratori di zona impostano il tempo di vita (TTL) per i singoli record e i resolver utilizzano queste informazioni per memorizzare i record.","canonical_url":"https:\/\/prohoster.info\/it\/blog\/administrirovanie\/hvatit-ispolzovat-smehotvorno-malyj-ttl-dlya-dns","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"it_IT","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0425\u0432\u0430\u0442\u0438\u0442 \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u044c \u0441\u043c\u0435\u0445\u043e\u0442\u0432\u043e\u0440\u043d\u043e \u043c\u0430\u043b\u044b\u0439 TTL 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