{"id":27822,"date":"2025-05-03T16:13:20","date_gmt":"2025-05-03T09:13:20","guid":{"rendered":"https:\/\/interdata.vn\/blog\/?p=27822"},"modified":"2025-05-03T16:13:20","modified_gmt":"2025-05-03T09:13:20","slug":"ttl-la-gi","status":"publish","type":"post","link":"https:\/\/interdata.vn\/blog\/ttl-la-gi\/","title":{"rendered":"TTL l\u00e0 g\u00ec? H\u01b0\u1edbng d\u1eabn A-Z v\u1ec1 Time To Live trong DNS"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-white ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">N\u1ed8I DUNG<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 eztoc-toggle-hide-by-default' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#TTL-Time-To-Live-la-gi\" >TTL (Time To Live) l\u00e0 g\u00ec?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#TTL-hoat-dong-nhu-the-nao-trong-he-thong-DNS\" >TTL ho\u1ea1t \u0111\u1ed9ng nh\u01b0 th\u1ebf n\u00e0o trong h\u1ec7 th\u1ed1ng DNS?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Quy-trinh-phan-giai-ten-mien-vai-tro-cua-DNS-Cache\" >Quy tr\u00ecnh ph\u00e2n gi\u1ea3i t\u00ean mi\u1ec1n &amp; vai tr\u00f2 c\u1ee7a DNS Cache<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#TTL-xac-dinh-thoi-gian-luu-Cache-ra-sao\" >TTL x\u00e1c \u0111\u1ecbnh th\u1eddi gian l\u01b0u Cache ra sao?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Vi-du-ve-luong-hoat-dong-cua-TTL\" >V\u00ed d\u1ee5 v\u1ec1 lu\u1ed3ng ho\u1ea1t \u0111\u1ed9ng c\u1ee7a TTL<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Tai-sao-TTL-lai-quan-trong-Anh-huong-chinh-cua-TTL\" >T\u1ea1i sao TTL l\u1ea1i quan tr\u1ecdng? \u1ea2nh h\u01b0\u1edfng ch\u00ednh c\u1ee7a TTL<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Anh-huong-den-toc-do-Lan-truyen-DNS-DNS-Propagation\" >\u1ea2nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 Lan truy\u1ec1n DNS (DNS Propagation)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Anh-huong-den-tai-cua-may-chu-DNS-Server-Load\" >\u1ea2nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ea3i c\u1ee7a m\u00e1y ch\u1ee7 DNS (Server Load)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Anh-huong-den-trai-nghiem-nguoi-dung-va-hieu-suat-Website\" >\u1ea2nh h\u01b0\u1edfng \u0111\u1ebfn tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng v\u00e0 hi\u1ec7u su\u1ea5t Website<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Cac-loai-ban-ghi-DNS-va-gia-tri-TTL-pho-bien\" >C\u00e1c lo\u1ea1i b\u1ea3n ghi DNS v\u00e0 gi\u00e1 tr\u1ecb TTL ph\u1ed5 bi\u1ebfn<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#TTL-cho-cac-ban-ghi-pho-bien-A-CNAME-MX-TXT-NS\" >TTL cho c\u00e1c b\u1ea3n ghi ph\u1ed5 bi\u1ebfn (A, CNAME, MX, TXT, NS)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Gia-tri-TTL-mac-dinh-va-khuyen-nghi\" >Gi\u00e1 tr\u1ecb TTL m\u1eb7c \u0111\u1ecbnh v\u00e0 khuy\u1ebfn ngh\u1ecb<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Nen-dat-gia-tri-TTL-bao-nhieu-la-phu-hop\" >N\u00ean \u0111\u1eb7t gi\u00e1 tr\u1ecb TTL bao nhi\u00eau l\u00e0 ph\u00f9 h\u1ee3p?<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Huong-dan-cach-kiem-tra-gia-tri-TTL-cua-ten-mien\" >H\u01b0\u1edbng d\u1eabn c\u00e1ch ki\u1ec3m tra gi\u00e1 tr\u1ecb TTL c\u1ee7a t\u00ean mi\u1ec1n<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Kiem-tra-TTL-bang-Cong-cu-Online-DNS-Checker-Tools\" >Ki\u1ec3m tra TTL b\u1eb1ng C\u00f4ng c\u1ee5 Online (DNS Checker Tools)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Kiem-tra-TTL-bang-Dong-lenh-Command-Line\" >Ki\u1ec3m tra TTL b\u1eb1ng D\u00f2ng l\u1ec7nh (Command Line)<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Luu-y-quan-trong-khi-Thay-doi-gia-tri-TTL\" >L\u01b0u \u00fd quan tr\u1ecdng khi Thay \u0111\u1ed5i gi\u00e1 tr\u1ecb TTL<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Nen-giam-TTL-truoc-khi-thuc-hien-thay-doi-DNS-quan-trong\" >N\u00ean gi\u1ea3m TTL tr\u01b0\u1edbc khi th\u1ef1c hi\u1ec7n thay \u0111\u1ed5i DNS quan tr\u1ecdng<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Thoi-gian-cho-sau-khi-thay-doi-TTL\" >Th\u1eddi gian ch\u1edd sau khi thay \u0111\u1ed5i TTL<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Cau-hoi-thuong-gap-ve-TTL-FAQ\" >C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p v\u1ec1 TTL (FAQ)<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#TTL-1-giay-co-y-nghia-gi\" >TTL 1 gi\u00e2y c\u00f3 \u00fd ngh\u0129a g\u00ec?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-22\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#TTL-300-5-phut-co-tot-khong\" >TTL 300 (5 ph\u00fat) c\u00f3 t\u1ed1t kh\u00f4ng?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-23\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#TTL-va-Ping-khac-nhau-nhu-the-nao\" >TTL v\u00e0 Ping kh\u00e1c nhau nh\u01b0 th\u1ebf n\u00e0o?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-24\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Thay-doi-TTL-co-lam-website-bi-gian-doan-downtime-khong\" >Thay \u0111\u1ed5i TTL c\u00f3 l\u00e0m website b\u1ecb gi\u00e1n \u0111o\u1ea1n (downtime) kh\u00f4ng?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-25\" href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/#Nha-cung-cap-hostingten-mien-cua-toi-dat-TTL-mac-dinh-la-bao-nhieu\" >Nh\u00e0 cung c\u1ea5p hosting\/t\u00ean mi\u1ec1n c\u1ee7a t\u00f4i \u0111\u1eb7t TTL m\u1eb7c \u0111\u1ecbnh l\u00e0 bao nhi\u00eau?<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n\n<p>TTL (Time To Live) l\u00e0 m\u1ed9t gi\u00e1 tr\u1ecb c\u00e0i \u0111\u1eb7t cho bi\u1ebft kho\u1ea3ng th\u1eddi gian m\u1ed9t b\u1ea3n ghi DNS \u0111\u01b0\u1ee3c ph\u00e9p l\u01b0u tr\u1eef trong b\u1ed9 nh\u1edb \u0111\u1ec7m (cache). Th\u00f4ng s\u1ed1 n\u00e0y r\u1ea5t quan tr\u1ecdng cho vi\u1ec7c qu\u1ea3n l\u00fd t\u00ean mi\u1ec1n v\u00e0 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 c\u1eadp nh\u1eadt th\u00f4ng tin DNS c\u1ee7a website b\u1ea1n.<\/p>\n<p>Hi\u1ec3u r\u00f5 v\u1ec1 TTL gi\u00fap b\u1ea1n ch\u1ee7 \u0111\u1ed9ng h\u01a1n khi th\u1ef1c hi\u1ec7n c\u00e1c thay \u0111\u1ed5i li\u00ean quan \u0111\u1ebfn hosting ho\u1eb7c c\u1ea5u h\u00ecnh t\u00ean mi\u1ec1n. B\u00e0i vi\u1ebft n\u00e0y s\u1ebd gi\u1ea3i th\u00edch to\u00e0n di\u1ec7n TTL l\u00e0 g\u00ec, c\u00e1ch ho\u1ea1t \u0111\u1ed9ng, t\u1ea7m quan tr\u1ecdng, c\u00e1ch ki\u1ec3m tra v\u00e0 l\u1ef1a ch\u1ecdn gi\u00e1 tr\u1ecb ph\u00f9 h\u1ee3p, gi\u00fap b\u1ea1n t\u1ed1i \u01b0u h\u00f3a h\u1ec7 th\u1ed1ng DNS hi\u1ec7u qu\u1ea3.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"TTL-Time-To-Live-la-gi\"><\/span>TTL (Time To Live) l\u00e0 g\u00ec?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p data-sourcepos=\"5:1-5:238\"><a href=\"https:\/\/interdata.vn\/blog\/ttl-la-gi\/\">TTL (Time To Live)<\/a> l\u00e0 m\u1ed9t c\u00e0i \u0111\u1eb7t DNS ch\u1ec9 \u0111\u1ecbnh kho\u1ea3ng th\u1eddi gian m\u1ed9t b\u1ea3n ghi DNS (DNS record) \u0111\u01b0\u1ee3c ph\u00e9p t\u1ed3n t\u1ea1i ho\u1eb7c l\u01b0u tr\u1eef trong b\u1ed9 nh\u1edb \u0111\u1ec7m (cache) c\u1ee7a m\u1ed9t m\u00e1y ch\u1ee7 DNS trung gian (resolver). Gi\u00e1 tr\u1ecb n\u00e0y th\u01b0\u1eddng \u0111\u01b0\u1ee3c t\u00ednh b\u1eb1ng \u0111\u01a1n v\u1ecb gi\u00e2y.<\/p>\n<p data-sourcepos=\"5:1-5:238\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL.jpg\" alt=\"Time to live (TTL)\" width=\"750\" height=\"500\" class=\"aligncenter size-full wp-image-27826\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL.jpg 750w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-300x200.jpg 300w\" sizes=\"auto, (max-width: 750px) 100vw, 750px\" \/><\/p>\n<p data-sourcepos=\"7:1-7:244\">H\u00e3y h\u00ecnh dung TTL gi\u1ed1ng nh\u01b0 &#8220;h\u1ea1n s\u1eed d\u1ee5ng&#8221; \u0111\u01b0\u1ee3c g\u00e1n cho th\u00f4ng tin DNS. Khi kho\u1ea3ng th\u1eddi gian n\u00e0y k\u1ebft th\u00fac, m\u00e1y ch\u1ee7 resolver ph\u1ea3i y\u00eau c\u1ea7u l\u1ea1i th\u00f4ng tin m\u1edbi nh\u1ea5t t\u1eeb m\u00e1y ch\u1ee7 DNS g\u1ed1c (authoritative DNS server) thay v\u00ec s\u1eed d\u1ee5ng d\u1eef li\u1ec7u \u0111\u00e3 l\u01b0u tr\u01b0\u1edbc \u0111\u00f3.<\/p>\n<p data-sourcepos=\"9:1-9:262\">Ng\u01b0\u1eddi qu\u1ea3n tr\u1ecb m\u1ea1ng ho\u1eb7c ch\u1ee7 s\u1edf h\u1eefu website thi\u1ebft l\u1eadp gi\u00e1 tr\u1ecb TTL cho m\u1ed7i b\u1ea3n ghi DNS c\u1ee5 th\u1ec3 (v\u00ed d\u1ee5: b\u1ea3n ghi A, b\u1ea3n ghi MX, b\u1ea3n ghi CNAME) trong ph\u1ea7n c\u00e0i \u0111\u1eb7t c\u1ea5u h\u00ecnh t\u00ean mi\u1ec1n. Vi\u1ec7c n\u00e0y th\u01b0\u1eddng th\u1ef1c hi\u1ec7n qua b\u1ea3ng \u0111i\u1ec1u khi\u1ec3n c\u1ee7a nh\u00e0 cung c\u1ea5p t\u00ean mi\u1ec1n ho\u1eb7c hosting.<\/p>\n<p data-sourcepos=\"11:1-11:251\">V\u00ed d\u1ee5, m\u1ed9t gi\u00e1 tr\u1ecb TTL l\u00e0 3600 c\u00f3 ngh\u0129a l\u00e0 th\u00f4ng tin c\u1ee7a b\u1ea3n ghi DNS \u0111\u00f3 s\u1ebd \u0111\u01b0\u1ee3c c\u00e1c m\u00e1y ch\u1ee7 resolver l\u01b0u trong b\u1ed9 nh\u1edb \u0111\u1ec7m t\u1ed1i \u0111a 3600 gi\u00e2y (t\u01b0\u01a1ng \u0111\u01b0\u01a1ng 1 gi\u1edd). Sau 1 gi\u1edd, resolver s\u1ebd c\u1ea7n truy v\u1ea5n l\u1ea1i m\u00e1y ch\u1ee7 DNS g\u1ed1c \u0111\u1ec3 l\u1ea5y th\u00f4ng tin c\u1eadp nh\u1eadt (n\u1ebfu c\u00f3).<\/p>\n<p data-sourcepos=\"13:1-13:190\">Th\u00f4ng s\u1ed1 TTL n\u00e0y \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng, \u1ea3nh h\u01b0\u1edfng tr\u1ef1c ti\u1ebfp \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 c\u00e1c thay \u0111\u1ed5i v\u1ec1 DNS \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt tr\u00ean internet. Qu\u00e1 tr\u00ecnh c\u1eadp nh\u1eadt n\u00e0y \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 lan truy\u1ec1n DNS (DNS propagation).<\/p>\n<h2><span class=\"ez-toc-section\" id=\"TTL-hoat-dong-nhu-the-nao-trong-he-thong-DNS\"><\/span>TTL ho\u1ea1t \u0111\u1ed9ng nh\u01b0 th\u1ebf n\u00e0o trong h\u1ec7 th\u1ed1ng DNS?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u0110\u1ec3 hi\u1ec3u r\u00f5 TTL, ch\u00fang ta c\u1ea7n xem x\u00e9t c\u00e1ch H\u1ec7 th\u1ed1ng t\u00ean mi\u1ec1n &#8211; <strong>DNS (Domain Name System)<\/strong> &#8211; ho\u1ea1t \u0111\u1ed9ng v\u00e0 vai tr\u00f2 c\u1ee7a b\u1ed9 nh\u1edb \u0111\u1ec7m trong qu\u00e1 tr\u00ecnh n\u00e0y. DNS gi\u1ed1ng nh\u01b0 danh b\u1ea1 \u0111i\u1ec7n tho\u1ea1i c\u1ee7a internet, gi\u00fap d\u1ecbch t\u00ean mi\u1ec1n (d\u1ec5 nh\u1edb cho ng\u01b0\u1eddi) th\u00e0nh \u0111\u1ecba ch\u1ec9 IP (m\u00e1y t\u00ednh hi\u1ec3u).<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-02.jpg\" alt=\"Time to live (TTL) 02\" width=\"750\" height=\"511\" class=\"aligncenter size-full wp-image-27824\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-02.jpg 750w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-02-300x204.jpg 300w\" sizes=\"auto, (max-width: 750px) 100vw, 750px\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Quy-trinh-phan-giai-ten-mien-vai-tro-cua-DNS-Cache\"><\/span>Quy tr\u00ecnh ph\u00e2n gi\u1ea3i t\u00ean mi\u1ec1n &amp; vai tr\u00f2 c\u1ee7a DNS Cache<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Khi b\u1ea1n g\u00f5 m\u1ed9t t\u00ean mi\u1ec1n (v\u00ed d\u1ee5: <code>google.com<\/code>) v\u00e0o tr\u00ecnh duy\u1ec7t, m\u00e1y t\u00ednh c\u1ee7a b\u1ea1n c\u1ea7n t\u00ecm ra \u0111\u1ecba ch\u1ec9 IP t\u01b0\u01a1ng \u1ee9ng \u0111\u1ec3 k\u1ebft n\u1ed1i \u0111\u1ebfn m\u00e1y ch\u1ee7 web. Qu\u00e1 tr\u00ecnh n\u00e0y g\u1ecdi l\u00e0 ph\u00e2n gi\u1ea3i t\u00ean mi\u1ec1n (DNS lookup) v\u00e0 di\u1ec5n ra theo c\u00e1c b\u01b0\u1edbc c\u01a1 b\u1ea3n sau:<\/p>\n<ol>\n<li>M\u00e1y t\u00ednh ki\u1ec3m tra cache c\u1ee5c b\u1ed9 (trong h\u1ec7 \u0111i\u1ec1u h\u00e0nh ho\u1eb7c tr\u00ecnh duy\u1ec7t) xem c\u00f3 l\u01b0u th\u00f4ng tin IP c\u1ee7a t\u00ean mi\u1ec1n n\u00e0y kh\u00f4ng v\u00e0 c\u00f2n h\u1ea1n (TTL) kh\u00f4ng. N\u1ebfu c\u00f3, d\u00f9ng ngay th\u00f4ng tin n\u00e0y.<\/li>\n<li>N\u1ebfu kh\u00f4ng c\u00f3 trong cache c\u1ee5c b\u1ed9, m\u00e1y t\u00ednh g\u1eedi y\u00eau c\u1ea7u \u0111\u1ebfn m\u00e1y ch\u1ee7 DNS resolver (th\u01b0\u1eddng do nh\u00e0 cung c\u1ea5p m\u1ea1ng ISP cung c\u1ea5p, ho\u1eb7c b\u1ea1n t\u1ef1 c\u1ea5u h\u00ecnh nh\u01b0 DNS Google 8.8.8.8).<\/li>\n<li>M\u00e1y ch\u1ee7 DNS resolver ki\u1ec3m tra b\u1ed9 nh\u1edb \u0111\u1ec7m (cache) c\u1ee7a ch\u00ednh n\u00f3. N\u1ebfu c\u00f3 th\u00f4ng tin IP c\u1ee7a t\u00ean mi\u1ec1n v\u00e0 c\u00f2n h\u1ea1n TTL, n\u00f3 tr\u1ea3 k\u1ebft qu\u1ea3 v\u1ec1 cho m\u00e1y t\u00ednh c\u1ee7a b\u1ea1n.<\/li>\n<li>N\u1ebfu resolver c\u0169ng kh\u00f4ng c\u00f3 cache ho\u1eb7c cache \u0111\u00e3 h\u1ebft h\u1ea1n TTL, n\u00f3 s\u1ebd b\u1eaft \u0111\u1ea7u qu\u00e1 tr\u00ecnh truy v\u1ea5n \u0111\u1ec7 quy: h\u1ecfi m\u00e1y ch\u1ee7 DNS g\u1ed1c (Root DNS server), r\u1ed3i m\u00e1y ch\u1ee7 TLD (qu\u1ea3n l\u00fd t\u00ean mi\u1ec1n c\u1ea5p cao nh\u01b0 .com, .vn), v\u00e0 cu\u1ed1i c\u00f9ng l\u00e0 m\u00e1y ch\u1ee7 DNS Authoritative (m\u00e1y ch\u1ee7 ch\u1ee9a th\u00f4ng tin g\u1ed1c c\u1ee7a t\u00ean mi\u1ec1n \u0111\u00f3).<\/li>\n<li>M\u00e1y ch\u1ee7 Authoritative tr\u1ea3 v\u1ec1 \u0111\u1ecba ch\u1ec9 IP (v\u00e0 th\u00f4ng tin TTL c\u1ee7a b\u1ea3n ghi) cho resolver.<\/li>\n<li>Resolver l\u01b0u th\u00f4ng tin n\u00e0y v\u00e0o cache c\u1ee7a m\u00ecnh (theo th\u1eddi gian TTL nh\u1eadn \u0111\u01b0\u1ee3c) v\u00e0 g\u1eedi k\u1ebft qu\u1ea3 IP v\u1ec1 cho m\u00e1y t\u00ednh c\u1ee7a b\u1ea1n.<\/li>\n<li>M\u00e1y t\u00ednh c\u1ee7a b\u1ea1n nh\u1eadn IP v\u00e0 k\u1ebft n\u1ed1i \u0111\u1ebfn m\u00e1y ch\u1ee7 web.<\/li>\n<\/ol>\n<p><strong>DNS Cache (B\u1ed9 nh\u1edb \u0111\u1ec7m DNS)<\/strong> \u0111\u00f3ng vai tr\u00f2 then ch\u1ed1t trong vi\u1ec7c t\u0103ng t\u1ed1c \u0111\u1ed9 truy c\u1eadp v\u00e0 gi\u1ea3m t\u1ea3i cho h\u1ec7 th\u1ed1ng DNS to\u00e0n c\u1ea7u. Thay v\u00ec ph\u1ea3i truy v\u1ea5n t\u1eeb g\u1ed1c m\u1ed7i l\u1ea7n, c\u00e1c resolver c\u00f3 th\u1ec3 tr\u1ea3 l\u1eddi nhanh ch\u00f3ng t\u1eeb cache.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"TTL-xac-dinh-thoi-gian-luu-Cache-ra-sao\"><\/span>TTL x\u00e1c \u0111\u1ecbnh th\u1eddi gian l\u01b0u Cache ra sao?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>TTL ch\u00ednh l\u00e0 y\u1ebfu t\u1ed1 quy\u1ebft \u0111\u1ecbnh th\u00f4ng tin \u0111\u01b0\u1ee3c l\u01b0u trong DNS cache bao l\u00e2u. Khi m\u1ed9t DNS resolver nh\u1eadn \u0111\u01b0\u1ee3c th\u00f4ng tin v\u1ec1 m\u1ed9t b\u1ea3n ghi DNS t\u1eeb m\u00e1y ch\u1ee7 authoritative, th\u00f4ng tin \u0111\u00f3 \u0111i k\u00e8m v\u1edbi m\u1ed9t gi\u00e1 tr\u1ecb TTL.<\/p>\n<p>Resolver s\u1ebd l\u01b0u b\u1ea3n ghi n\u00e0y v\u00e0o cache v\u00e0 b\u1eaft \u0111\u1ea7u \u0111\u1ebfm ng\u01b0\u1ee3c th\u1eddi gian TTL. Ch\u1eebng n\u00e0o b\u1ed9 \u0111\u1ebfm c\u00f2n l\u1edbn h\u01a1n 0, b\u1ea3n ghi trong cache \u0111\u01b0\u1ee3c coi l\u00e0 h\u1ee3p l\u1ec7 v\u00e0 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 tr\u1ea3 l\u1eddi c\u00e1c truy v\u1ea5n ti\u1ebfp theo cho c\u00f9ng t\u00ean mi\u1ec1n \u0111\u00f3.<\/p>\n<p>Khi b\u1ed9 \u0111\u1ebfm TTL v\u1ec1 \u0111\u1ebfn 0, b\u1ea3n ghi trong cache b\u1ecb coi l\u00e0 &#8220;h\u1ebft h\u1ea1n&#8221; ho\u1eb7c &#8220;kh\u00f4ng h\u1ee3p l\u1ec7&#8221;. L\u1ea7n ti\u1ebfp theo resolver nh\u1eadn \u0111\u01b0\u1ee3c y\u00eau c\u1ea7u cho t\u00ean mi\u1ec1n \u0111\u00f3, n\u00f3 b\u1eaft bu\u1ed9c ph\u1ea3i th\u1ef1c hi\u1ec7n l\u1ea1i quy tr\u00ecnh truy v\u1ea5n \u0111\u1ebfn m\u00e1y ch\u1ee7 authoritative \u0111\u1ec3 l\u1ea5y th\u00f4ng tin m\u1edbi nh\u1ea5t c\u00f9ng v\u1edbi gi\u00e1 tr\u1ecb TTL m\u1edbi.<\/p>\n<p>M\u1ed1i quan h\u1ec7 r\u1ea5t tr\u1ef1c ti\u1ebfp: Gi\u00e1 tr\u1ecb TTL b\u1ea1n \u0111\u1eb7t cho b\u1ea3n ghi DNS quy \u0111\u1ecbnh ch\u00ednh x\u00e1c kho\u1ea3ng th\u1eddi gian (t\u00ednh b\u1eb1ng gi\u00e2y) m\u00e0 c\u00e1c m\u00e1y ch\u1ee7 resolver tr\u00ean kh\u1eafp internet \u0111\u01b0\u1ee3c ph\u00e9p gi\u1eef l\u1ea1i th\u00f4ng tin \u0111\u00f3 trong b\u1ed9 nh\u1edb \u0111\u1ec7m c\u1ee7a ch\u00fang.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Vi-du-ve-luong-hoat-dong-cua-TTL\"><\/span>V\u00ed d\u1ee5 v\u1ec1 lu\u1ed3ng ho\u1ea1t \u0111\u1ed9ng c\u1ee7a TTL<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Gi\u1ea3 s\u1eed b\u1ea1n qu\u1ea3n l\u00fd t\u00ean mi\u1ec1n <code>vidu.com<\/code> v\u00e0 \u0111\u1eb7t TTL cho b\u1ea3n ghi A (tr\u1ecf \u0111\u1ebfn IP <code>192.0.2.1<\/code>) l\u00e0 3600 gi\u00e2y (1 gi\u1edd).<\/p>\n<ul>\n<li><strong>Th\u1eddi \u0111i\u1ec3m T=0:<\/strong> Ng\u01b0\u1eddi d\u00f9ng A truy c\u1eadp <code>vidu.com<\/code> l\u1ea7n \u0111\u1ea7u. M\u00e1y ch\u1ee7 DNS resolver c\u1ee7a h\u1ecd (Resolver X) kh\u00f4ng c\u00f3 cache. Resolver X truy v\u1ea5n m\u00e1y ch\u1ee7 authoritative, nh\u1eadn \u0111\u01b0\u1ee3c IP <code>192.0.2.1<\/code> v\u00e0 TTL <code>3600<\/code>. Resolver X l\u01b0u th\u00f4ng tin n\u00e0y v\u00e0o cache v\u00e0 b\u1eaft \u0111\u1ea7u \u0111\u1ebfm ng\u01b0\u1ee3c TTL. Ng\u01b0\u1eddi d\u00f9ng A truy c\u1eadp \u0111\u01b0\u1ee3c website.<\/li>\n<li><strong>Th\u1eddi \u0111i\u1ec3m T=30 ph\u00fat:<\/strong> Ng\u01b0\u1eddi d\u00f9ng B (c\u0169ng d\u00f9ng Resolver X) truy c\u1eadp <code>vidu.com<\/code>. Resolver X ki\u1ec3m tra cache, th\u1ea5y c\u00f3 th\u00f4ng tin IP <code>192.0.2.1<\/code> v\u00e0 TTL v\u1eabn c\u00f2n hi\u1ec7u l\u1ef1c (c\u00f2n 30 ph\u00fat). Resolver X tr\u1ea3 ngay k\u1ebft qu\u1ea3 t\u1eeb cache. Ng\u01b0\u1eddi d\u00f9ng B truy c\u1eadp website nhanh ch\u00f3ng.<\/li>\n<li><strong>Th\u1eddi \u0111i\u1ec3m T=1 gi\u1edd 10 ph\u00fat:<\/strong> Ng\u01b0\u1eddi d\u00f9ng C (c\u0169ng d\u00f9ng Resolver X) truy c\u1eadp <code>vidu.com<\/code>. Resolver X ki\u1ec3m tra cache, th\u1ea5y th\u00f4ng tin IP <code>192.0.2.1<\/code> nh\u01b0ng TTL \u0111\u00e3 v\u1ec1 0 (h\u1ebft h\u1ea1n). Resolver X ph\u1ea3i truy v\u1ea5n l\u1ea1i m\u00e1y ch\u1ee7 authoritative \u0111\u1ec3 l\u1ea5y th\u00f4ng tin m\u1edbi nh\u1ea5t (c\u00f3 th\u1ec3 v\u1eabn l\u00e0 <code>192.0.2.1<\/code> ho\u1eb7c IP kh\u00e1c n\u1ebfu b\u1ea1n \u0111\u00e3 thay \u0111\u1ed5i) c\u00f9ng TTL m\u1edbi. Sau \u0111\u00f3 m\u1edbi tr\u1ea3 k\u1ebft qu\u1ea3 cho ng\u01b0\u1eddi d\u00f9ng C.<\/li>\n<\/ul>\n<p>V\u00ed d\u1ee5 n\u00e0y cho th\u1ea5y TTL ki\u1ec3m so\u00e1t tr\u1ef1c ti\u1ebfp vi\u1ec7c s\u1eed d\u1ee5ng cache, \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 ph\u1ea3n h\u1ed3i c\u1ee7a DNS resolver v\u00e0 \u0111\u1ea3m b\u1ea3o th\u00f4ng tin \u0111\u01b0\u1ee3c l\u00e0m m\u1edbi sau m\u1ed9t kho\u1ea3ng th\u1eddi gian nh\u1ea5t \u0111\u1ecbnh.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Tai-sao-TTL-lai-quan-trong-Anh-huong-chinh-cua-TTL\"><\/span>T\u1ea1i sao TTL l\u1ea1i quan tr\u1ecdng? \u1ea2nh h\u01b0\u1edfng ch\u00ednh c\u1ee7a TTL<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Vi\u1ec7c hi\u1ec3u v\u00e0 c\u1ea5u h\u00ecnh \u0111\u00fang gi\u00e1 tr\u1ecb TTL kh\u00f4ng ch\u1ec9 l\u00e0 v\u1ea5n \u0111\u1ec1 k\u1ef9 thu\u1eadt thu\u1ea7n t\u00fay. N\u00f3 c\u00f3 nh\u1eefng \u1ea3nh h\u01b0\u1edfng th\u1ef1c t\u1ebf v\u00e0 quan tr\u1ecdng \u0111\u1ed1i v\u1edbi ho\u1ea1t \u0111\u1ed9ng c\u1ee7a website, h\u1ec7 th\u1ed1ng m\u1ea1ng v\u00e0 tr\u1ea3i nghi\u1ec7m c\u1ee7a ng\u01b0\u1eddi d\u00f9ng cu\u1ed1i.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-01.jpg\" alt=\"Time to live (TTL) 01\" width=\"750\" height=\"394\" class=\"aligncenter size-full wp-image-27823\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-01.jpg 750w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-01-300x158.jpg 300w\" sizes=\"auto, (max-width: 750px) 100vw, 750px\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Anh-huong-den-toc-do-Lan-truyen-DNS-DNS-Propagation\"><\/span>\u1ea2nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 Lan truy\u1ec1n DNS (DNS Propagation)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0110\u00e2y l\u00e0 t\u00e1c \u0111\u1ed9ng r\u00f5 r\u00e0ng v\u00e0 th\u01b0\u1eddng \u0111\u01b0\u1ee3c quan t\u00e2m nh\u1ea5t c\u1ee7a TTL. <strong>Lan truy\u1ec1n DNS (DNS Propagation)<\/strong> l\u00e0 qu\u00e1 tr\u00ecnh c\u00e1c thay \u0111\u1ed5i b\u1ea1n th\u1ef1c hi\u1ec7n tr\u00ean b\u1ea3n ghi DNS (v\u00ed d\u1ee5: \u0111\u1ed5i \u0111\u1ecba ch\u1ec9 IP m\u00e1y ch\u1ee7 web, thay \u0111\u1ed5i c\u1ea5u h\u00ecnh email MX record) \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt tr\u00ean c\u00e1c m\u00e1y ch\u1ee7 DNS resolver kh\u1eafp to\u00e0n c\u1ea7u.<\/p>\n<p>Th\u1eddi gian lan truy\u1ec1n n\u00e0y ph\u1ee5 thu\u1ed9c l\u1edbn v\u00e0o gi\u00e1 tr\u1ecb TTL <i>tr\u01b0\u1edbc khi<\/i> b\u1ea1n th\u1ef1c hi\u1ec7n thay \u0111\u1ed5i. N\u1ebfu TTL c\u1ee7a b\u1ea3n ghi c\u0169 l\u00e0 86400 gi\u00e2y (24 gi\u1edd), c\u00e1c resolver c\u00f3 th\u1ec3 gi\u1eef th\u00f4ng tin c\u0169 trong t\u1ed1i \u0111a 24 gi\u1edd tr\u01b0\u1edbc khi ch\u00fang ki\u1ec3m tra l\u1ea1i v\u00e0 nh\u1eadn \u0111\u01b0\u1ee3c th\u00f4ng tin m\u1edbi c\u1ee7a b\u1ea1n.<\/p>\n<p>Ng\u01b0\u1ee3c l\u1ea1i, n\u1ebfu TTL ch\u1ec9 l\u00e0 300 gi\u00e2y (5 ph\u00fat), th\u00ec c\u00e1c resolver s\u1ebd c\u1eadp nh\u1eadt th\u00f4ng tin m\u1edbi c\u1ee7a b\u1ea1n nhanh h\u01a1n nhi\u1ec1u, th\u01b0\u1eddng trong v\u00f2ng v\u00e0i ph\u00fat \u0111\u1ebfn t\u1ed1i \u0111a 5 ph\u00fat sau khi ch\u00fang h\u1ebft h\u1ea1n cache c\u0169.<\/p>\n<p>Do \u0111\u00f3, TTL th\u1ea5p gi\u00fap t\u0103ng t\u1ed1c \u0111\u1ed9 lan truy\u1ec1n DNS, r\u1ea5t h\u1eefu \u00edch khi b\u1ea1n c\u1ea7n thay \u0111\u1ed5i c\u1ea5u h\u00ecnh DNS nhanh ch\u00f3ng (v\u00ed d\u1ee5: chuy\u1ec3n hosting, kh\u1eafc ph\u1ee5c s\u1ef1 c\u1ed1). TTL cao s\u1ebd l\u00e0m ch\u1eadm qu\u00e1 tr\u00ecnh c\u1eadp nh\u1eadt n\u00e0y.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Anh-huong-den-tai-cua-may-chu-DNS-Server-Load\"><\/span>\u1ea2nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ea3i c\u1ee7a m\u00e1y ch\u1ee7 DNS (Server Load)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>M\u1ed7i khi m\u1ed9t DNS resolver ph\u1ea3i truy v\u1ea5n m\u00e1y ch\u1ee7 DNS authoritative (v\u00ec cache kh\u00f4ng c\u00f3 ho\u1eb7c \u0111\u00e3 h\u1ebft h\u1ea1n TTL), h\u00e0nh \u0111\u1ed9ng n\u00e0y t\u1ea1o ra m\u1ed9t l\u01b0\u1ee3ng t\u1ea3i nh\u1ea5t \u0111\u1ecbnh l\u00ean m\u00e1y ch\u1ee7 authoritative \u0111\u00f3.<\/p>\n<p>N\u1ebfu b\u1ea1n \u0111\u1eb7t TTL qu\u00e1 th\u1ea5p cho c\u00e1c b\u1ea3n ghi DNS c\u1ee7a m\u00ecnh (v\u00ed d\u1ee5: 60 gi\u00e2y), c\u00e1c resolver tr\u00ean kh\u1eafp th\u1ebf gi\u1edbi s\u1ebd ph\u1ea3i li\u00ean t\u1ee5c h\u1ecfi l\u1ea1i m\u00e1y ch\u1ee7 authoritative c\u1ee7a b\u1ea1n. V\u1edbi m\u1ed9t website c\u00f3 l\u01b0u l\u01b0\u1ee3ng truy c\u1eadp l\u1edbn, \u0111i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 t\u1ea1o ra m\u1ed9t l\u01b0\u1ee3ng truy v\u1ea5n DNS kh\u1ed5ng l\u1ed3.<\/p>\n<p>L\u01b0\u1ee3ng truy v\u1ea5n l\u1edbn li\u00ean t\u1ee5c c\u00f3 th\u1ec3 l\u00e0m t\u0103ng \u0111\u00e1ng k\u1ec3 vi\u1ec7c s\u1eed d\u1ee5ng CPU, b\u1ed9 nh\u1edb v\u00e0 b\u0103ng th\u00f4ng tr\u00ean m\u00e1y ch\u1ee7 DNS authoritative. Trong m\u1ed9t s\u1ed1 tr\u01b0\u1eddng h\u1ee3p, \u0111\u1eb7c bi\u1ec7t l\u00e0 v\u1edbi c\u00e1c nh\u00e0 cung c\u1ea5p DNS t\u00ednh ph\u00ed theo l\u01b0\u1ee3t truy v\u1ea5n ho\u1eb7c h\u1ea1 t\u1ea7ng kh\u00f4ng \u0111\u1ee7 m\u1ea1nh, \u0111i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 g\u00e2y t\u1ed1n k\u00e9m ho\u1eb7c l\u00e0m gi\u1ea3m hi\u1ec7u su\u1ea5t ph\u1ea3n h\u1ed3i c\u1ee7a m\u00e1y ch\u1ee7 DNS.<\/p>\n<p>Ng\u01b0\u1ee3c l\u1ea1i, \u0111\u1eb7t TTL cao h\u01a1n (v\u00ed d\u1ee5: 14400 gi\u00e2y &#8211; 4 gi\u1edd) s\u1ebd gi\u1ea3m \u0111\u00e1ng k\u1ec3 s\u1ed1 l\u01b0\u1ee3t truy v\u1ea5n \u0111\u1ebfn m\u00e1y ch\u1ee7 authoritative, gi\u00fap gi\u1ea3m t\u1ea3i v\u00e0 ti\u1ebft ki\u1ec7m t\u00e0i nguy\u00ean. \u0110\u00e2y l\u00e0 s\u1ef1 \u0111\u00e1nh \u0111\u1ed5i gi\u1eefa t\u1ed1c \u0111\u1ed9 c\u1eadp nh\u1eadt v\u00e0 hi\u1ec7u qu\u1ea3 s\u1eed d\u1ee5ng t\u00e0i nguy\u00ean m\u00e1y ch\u1ee7.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Anh-huong-den-trai-nghiem-nguoi-dung-va-hieu-suat-Website\"><\/span>\u1ea2nh h\u01b0\u1edfng \u0111\u1ebfn tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng v\u00e0 hi\u1ec7u su\u1ea5t Website<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>TTL \u1ea3nh h\u01b0\u1edfng gi\u00e1n ti\u1ebfp \u0111\u1ebfn tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng v\u00e0 c\u1ea3m nh\u1eadn v\u1ec1 hi\u1ec7u su\u1ea5t website, \u0111\u1eb7c bi\u1ec7t l\u00e0 sau khi c\u00f3 thay \u0111\u1ed5i DNS.<\/p>\n<p>N\u1ebfu b\u1ea1n v\u1eeba \u0111\u1ed5i \u0111\u1ecba ch\u1ec9 IP hosting v\u00e0 TTL c\u0169 qu\u00e1 cao (v\u00ed d\u1ee5: 24 gi\u1edd), m\u1ed9t s\u1ed1 ng\u01b0\u1eddi d\u00f9ng c\u00f3 th\u1ec3 v\u1eabn truy c\u1eadp v\u00e0o \u0111\u1ecba ch\u1ec9 IP c\u0169 trong nhi\u1ec1u gi\u1edd sau \u0111\u00f3. \u0110i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn l\u1ed7i truy c\u1eadp, nh\u00ecn th\u1ea5y phi\u00ean b\u1ea3n website c\u0169, ho\u1eb7c kh\u00f4ng g\u1eedi\/nh\u1eadn \u0111\u01b0\u1ee3c email n\u1ebfu b\u1ea1n thay \u0111\u1ed5i b\u1ea3n ghi MX. Tr\u1ea3i nghi\u1ec7m n\u00e0y g\u00e2y kh\u00f3 ch\u1ecbu v\u00e0 thi\u1ebfu chuy\u00ean nghi\u1ec7p.<\/p>\n<p>M\u1eb7c d\u00f9 TTL kh\u00f4ng tr\u1ef1c ti\u1ebfp t\u0103ng t\u1ed1c \u0111\u1ed9 t\u1ea3i trang (page load speed) c\u1ee7a website, vi\u1ec7c ph\u00e2n gi\u1ea3i DNS nhanh ch\u00f3ng (nh\u1edd cache h\u1ee3p l\u1ec7 ho\u1eb7c TTL th\u1ea5p khi c\u1ea7n) l\u00e0 b\u01b0\u1edbc \u0111\u1ea7u ti\u00ean quan tr\u1ecdng \u0111\u1ec3 tr\u00ecnh duy\u1ec7t b\u1eaft \u0111\u1ea7u t\u1ea3i n\u1ed9i dung.<\/p>\n<p>C\u1ea5u h\u00ecnh TTL h\u1ee3p l\u00fd gi\u00fap \u0111\u1ea3m b\u1ea3o ng\u01b0\u1eddi d\u00f9ng lu\u00f4n truy c\u1eadp \u0111\u01b0\u1ee3c \u0111\u00fang m\u00e1y ch\u1ee7 v\u00e0 phi\u00ean b\u1ea3n website m\u1edbi nh\u1ea5t m\u1ed9t c\u00e1ch nhanh ch\u00f3ng sau c\u00e1c thay \u0111\u1ed5i, g\u00f3p ph\u1ea7n v\u00e0o tr\u1ea3i nghi\u1ec7m t\u1ed5ng th\u1ec3 t\u00edch c\u1ef1c.<\/p>\n<p>C\u1ea5u h\u00ecnh TTL h\u1ee3p l\u00fd gi\u00fap \u0111\u1ea3m b\u1ea3o ng\u01b0\u1eddi d\u00f9ng lu\u00f4n truy c\u1eadp \u0111\u01b0\u1ee3c \u0111\u00fang m\u00e1y ch\u1ee7 v\u00e0 phi\u00ean b\u1ea3n website m\u1edbi nh\u1ea5t m\u1ed9t c\u00e1ch nhanh ch\u00f3ng sau c\u00e1c thay \u0111\u1ed5i, g\u00f3p ph\u1ea7n v\u00e0o tr\u1ea3i nghi\u1ec7m t\u1ed5ng th\u1ec3 t\u00edch c\u1ef1c. B\u00ean c\u1ea1nh \u0111\u00f3, n\u1ec1n t\u1ea3ng hosting \u1ed5n \u0111\u1ecbnh c\u0169ng r\u1ea5t quan tr\u1ecdng.<\/p>\n<p>\u0110\u1ec3 website ho\u1ea1t \u0111\u1ed9ng \u1ed5n \u0111\u1ecbnh, t\u1ed1c \u0111\u1ed9 cao, b\u1ea1n c\u00f3 th\u1ec3 <strong><a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/interdata.vn\/thue-hosting\/\">thu\u00ea Hosting<\/a><\/strong> ch\u1ea5t l\u01b0\u1ee3ng t\u1ea1i InterData. Ch\u1ec9 t\u1eeb 1K\/ng\u00e0y, s\u1eed d\u1ee5ng ph\u1ea7n c\u1ee9ng chuy\u00ean d\u1ee5ng th\u1ebf h\u1ec7 m\u1edbi nh\u01b0 AMD EPYC Gen 3th, SSD NVMe U.2, mang \u0111\u1ebfn c\u1ea5u h\u00ecnh m\u1ea1nh, b\u0103ng th\u00f4ng cao, \u0111\u01b0\u1ee3c nhi\u1ec1u kh\u00e1ch h\u00e0ng tin d\u00f9ng.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cac-loai-ban-ghi-DNS-va-gia-tri-TTL-pho-bien\"><\/span>C\u00e1c lo\u1ea1i b\u1ea3n ghi DNS v\u00e0 gi\u00e1 tr\u1ecb TTL ph\u1ed5 bi\u1ebfn<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>TTL kh\u00f4ng ph\u1ea3i l\u00e0 m\u1ed9t c\u00e0i \u0111\u1eb7t chung cho to\u00e0n b\u1ed9 t\u00ean mi\u1ec1n m\u00e0 \u0111\u01b0\u1ee3c thi\u1ebft l\u1eadp ri\u00eang cho t\u1eebng <strong>b\u1ea3n ghi DNS (DNS Record)<\/strong>. M\u1ed7i lo\u1ea1i b\u1ea3n ghi ph\u1ee5c v\u1ee5 m\u1ed9t m\u1ee5c \u0111\u00edch kh\u00e1c nhau trong vi\u1ec7c \u0111\u1ecbnh tuy\u1ebfn v\u00e0 c\u1ea5u h\u00ecnh d\u1ecbch v\u1ee5 cho t\u00ean mi\u1ec1n.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"TTL-cho-cac-ban-ghi-pho-bien-A-CNAME-MX-TXT-NS\"><\/span>TTL cho c\u00e1c b\u1ea3n ghi ph\u1ed5 bi\u1ebfn (A, CNAME, MX, TXT, NS)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>D\u01b0\u1edbi \u0111\u00e2y l\u00e0 m\u1ed9t s\u1ed1 lo\u1ea1i b\u1ea3n ghi DNS quan tr\u1ecdng v\u00e0 \u00fd ngh\u0129a c\u1ee7a TTL \u0111\u1ed1i v\u1edbi ch\u00fang:<\/p>\n<ul>\n<li><strong>B\u1ea3n ghi A (Address Mapping):<\/strong> Tr\u1ecf m\u1ed9t t\u00ean mi\u1ec1n (ho\u1eb7c subdomain) \u0111\u1ebfn m\u1ed9t \u0111\u1ecba ch\u1ec9 IPv4. TTL cho b\u1ea3n ghi A quy\u1ebft \u0111\u1ecbnh t\u1ed1c \u0111\u1ed9 c\u1eadp nh\u1eadt khi b\u1ea1n thay \u0111\u1ed5i \u0111\u1ecba ch\u1ec9 IP hosting c\u1ee7a website.<\/li>\n<li><strong>B\u1ea3n ghi AAAA (IPv6 Address Mapping):<\/strong> T\u01b0\u01a1ng t\u1ef1 b\u1ea3n ghi A nh\u01b0ng d\u00e0nh cho \u0111\u1ecba ch\u1ec9 IPv6. TTL c\u0169ng \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 c\u1eadp nh\u1eadt khi \u0111\u1ed5i IP IPv6.<\/li>\n<li><strong>B\u1ea3n ghi CNAME (Canonical Name):<\/strong> Tr\u1ecf m\u1ed9t t\u00ean mi\u1ec1n\/subdomain (b\u00ed danh) \u0111\u1ebfn m\u1ed9t t\u00ean mi\u1ec1n kh\u00e1c (t\u00ean ch\u00ednh t\u1eafc). TTL \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn th\u1eddi gian c\u1eadp nh\u1eadt n\u1ebfu t\u00ean mi\u1ec1n ch\u00ednh t\u1eafc thay \u0111\u1ed5i IP. L\u01b0u \u00fd: TTL c\u1ee7a b\u1ea3n ghi CNAME th\u01b0\u1eddng \u0111\u01b0\u1ee3c \u01b0u ti\u00ean h\u01a1n TTL c\u1ee7a b\u1ea3n ghi A m\u00e0 n\u00f3 tr\u1ecf t\u1edbi trong m\u1ed9t s\u1ed1 resolver.<\/li>\n<li><strong>B\u1ea3n ghi MX (Mail Exchanger):<\/strong> Ch\u1ec9 \u0111\u1ecbnh m\u00e1y ch\u1ee7 email ch\u1ecbu tr\u00e1ch nhi\u1ec7m nh\u1eadn th\u01b0 cho t\u00ean mi\u1ec1n. TTL cho b\u1ea3n ghi MX r\u1ea5t quan tr\u1ecdng khi b\u1ea1n thay \u0111\u1ed5i nh\u00e0 cung c\u1ea5p email ho\u1eb7c c\u1ea5u h\u00ecnh m\u00e1y ch\u1ee7 th\u01b0. TTL th\u1ea5p gi\u00fap chuy\u1ec3n \u0111\u1ed5i di\u1ec5n ra nhanh h\u01a1n.<\/li>\n<li><strong>B\u1ea3n ghi TXT (Text):<\/strong> Cho ph\u00e9p l\u01b0u tr\u1eef th\u00f4ng tin d\u1ea1ng v\u0103n b\u1ea3n. Th\u01b0\u1eddng d\u00f9ng cho c\u00e1c m\u1ee5c \u0111\u00edch x\u00e1c th\u1ef1c (SPF, DKIM, DMARC cho email, x\u00e1c minh s\u1edf h\u1eefu t\u00ean mi\u1ec1n v\u1edbi Google&#8230;). TTL cho b\u1ea3n ghi TXT \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 c\u00e1c d\u1ecbch v\u1ee5 x\u00e1c th\u1ef1c nh\u1eadn ra thay \u0111\u1ed5i.<\/li>\n<li><strong>B\u1ea3n ghi NS (Name Server):<\/strong> Ch\u1ec9 \u0111\u1ecbnh c\u00e1c m\u00e1y ch\u1ee7 DNS authoritative cho t\u00ean mi\u1ec1n. Thay \u0111\u1ed5i b\u1ea3n ghi NS l\u00e0 m\u1ed9t thay \u0111\u1ed5i l\u1edbn, v\u00e0 TTL c\u1ee7a b\u1ea3n ghi NS (th\u01b0\u1eddng \u0111\u01b0\u1ee3c qu\u1ea3n l\u00fd \u1edf c\u1ea5p \u0111\u1ed9 nh\u00e0 \u0111\u0103ng k\u00fd t\u00ean mi\u1ec1n v\u00e0 TLD) quy\u1ebft \u0111\u1ecbnh t\u1ed1c \u0111\u1ed9 lan truy\u1ec1n c\u1ee7a vi\u1ec7c thay \u0111\u1ed5i m\u00e1y ch\u1ee7 qu\u1ea3n l\u00fd DNS. TTL cho NS th\u01b0\u1eddng kh\u00e1 cao (v\u00ed d\u1ee5: 48 gi\u1edd).<\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Gia-tri-TTL-mac-dinh-va-khuyen-nghi\"><\/span>Gi\u00e1 tr\u1ecb TTL m\u1eb7c \u0111\u1ecbnh v\u00e0 khuy\u1ebfn ngh\u1ecb<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Kh\u00f4ng c\u00f3 m\u1ed9t gi\u00e1 tr\u1ecb TTL &#8220;ho\u00e0n h\u1ea3o&#8221; cho t\u1ea5t c\u1ea3 m\u1ecdi tr\u01b0\u1eddng h\u1ee3p. C\u00e1c nh\u00e0 cung c\u1ea5p hosting v\u00e0 t\u00ean mi\u1ec1n th\u01b0\u1eddng \u0111\u1eb7t m\u1ed9t gi\u00e1 tr\u1ecb TTL m\u1eb7c \u0111\u1ecbnh, ph\u1ed5 bi\u1ebfn l\u00e0:<\/p>\n<ul>\n<li><strong>3600 gi\u00e2y (1 gi\u1edd):<\/strong> M\u1ee9c c\u00e2n b\u1eb1ng kh\u00e1 t\u1ed1t gi\u1eefa t\u1ed1c \u0111\u1ed9 c\u1eadp nh\u1eadt v\u00e0 gi\u1ea3m t\u1ea3i m\u00e1y ch\u1ee7.<\/li>\n<li><strong>14400 gi\u00e2y (4 gi\u1edd):<\/strong> Th\u01b0\u1eddng d\u00f9ng cho c\u00e1c b\u1ea3n ghi \u00edt thay \u0111\u1ed5i, gi\u00fap gi\u1ea3m t\u1ea3i hi\u1ec7u qu\u1ea3.<\/li>\n<li><strong>86400 gi\u00e2y (24 gi\u1edd):<\/strong> D\u00f9ng cho c\u00e1c b\u1ea3n ghi r\u1ea5t \u1ed5n \u0111\u1ecbnh, \u00edt khi c\u1ea7n thay \u0111\u1ed5i.<\/li>\n<\/ul>\n<p><strong>Khuy\u1ebfn ngh\u1ecb chung:<\/strong><\/p>\n<ul>\n<li><strong>Khi h\u1ec7 th\u1ed1ng \u1ed5n \u0111\u1ecbnh, \u00edt thay \u0111\u1ed5i:<\/strong> B\u1ea1n c\u00f3 th\u1ec3 \u0111\u1eb7t TTL cao (v\u00ed d\u1ee5: 1 gi\u1edd \u0111\u1ebfn 24 gi\u1edd) cho c\u00e1c b\u1ea3n ghi nh\u01b0 A, MX (n\u1ebfu kh\u00f4ng \u0111\u1ed5i IP\/email server th\u01b0\u1eddng xuy\u00ean) \u0111\u1ec3 gi\u1ea3m t\u1ea3i cho m\u00e1y ch\u1ee7 DNS v\u00e0 c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t DNS lookup t\u1eeb cache.<\/li>\n<li><strong>Khi chu\u1ea9n b\u1ecb thay \u0111\u1ed5i DNS l\u1edbn:<\/strong> (V\u00ed d\u1ee5: \u0111\u1ed5i IP hosting, chuy\u1ec3n nh\u00e0 cung c\u1ea5p email, thay \u0111\u1ed5i c\u1ea5u tr\u00fac website quan tr\u1ecdng) N\u00ean ch\u1ee7 \u0111\u1ed9ng <strong>gi\u1ea3m TTL<\/strong> xu\u1ed1ng m\u1ee9c th\u1ea5p (v\u00ed d\u1ee5: 300 gi\u00e2y\/5 ph\u00fat ho\u1eb7c th\u1eadm ch\u00ed 60 gi\u00e2y\/1 ph\u00fat) <strong>\u00edt nh\u1ea5t l\u00e0 b\u1eb1ng gi\u00e1 tr\u1ecb TTL c\u0169 tr\u01b0\u1edbc \u0111\u00f3<\/strong> (v\u00ed d\u1ee5: n\u1ebfu TTL c\u0169 l\u00e0 24 gi\u1edd, n\u00ean gi\u1ea3m tr\u01b0\u1edbc 24 gi\u1edd). Vi\u1ec7c n\u00e0y gi\u00fap thay \u0111\u1ed5i c\u1ee7a b\u1ea1n lan truy\u1ec1n nhanh ch\u00f3ng khi th\u1ef1c hi\u1ec7n.<\/li>\n<li><strong>Sau khi thay \u0111\u1ed5i ho\u00e0n t\u1ea5t v\u00e0 \u1ed5n \u0111\u1ecbnh:<\/strong> B\u1ea1n c\u00f3 th\u1ec3 t\u0103ng TTL tr\u1edf l\u1ea1i m\u1ee9c cao h\u01a1n \u0111\u1ec3 gi\u1ea3m t\u1ea3i.<\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Nen-dat-gia-tri-TTL-bao-nhieu-la-phu-hop\"><\/span>N\u00ean \u0111\u1eb7t gi\u00e1 tr\u1ecb TTL bao nhi\u00eau l\u00e0 ph\u00f9 h\u1ee3p?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Vi\u1ec7c l\u1ef1a ch\u1ecdn gi\u00e1 tr\u1ecb TTL t\u1ed1i \u01b0u ph\u1ee5 thu\u1ed9c v\u00e0o c\u00e1c y\u1ebfu t\u1ed1 sau:<\/p>\n<ol>\n<li><strong>T\u1ea7n su\u1ea5t thay \u0111\u1ed5i b\u1ea3n ghi:<\/strong> B\u1ea3n ghi n\u00e0o b\u1ea1n d\u1ef1 ki\u1ebfn s\u1ebd thay \u0111\u1ed5i th\u01b0\u1eddng xuy\u00ean (v\u00ed d\u1ee5: IP m\u00e1y ch\u1ee7 web n\u1ebfu d\u00f9ng c\u00e2n b\u1eb1ng t\u1ea3i \u0111\u1ed9ng) n\u00ean c\u00f3 TTL th\u1ea5p. B\u1ea3n ghi n\u00e0o g\u1ea7n nh\u01b0 kh\u00f4ng bao gi\u1edd \u0111\u1ed5i (v\u00ed d\u1ee5: b\u1ea3n ghi MX cho G Suite\/Microsoft 365) c\u00f3 th\u1ec3 \u0111\u1eb7t TTL cao.<\/li>\n<li><strong>T\u1ea7m quan tr\u1ecdng c\u1ee7a vi\u1ec7c c\u1eadp nh\u1eadt nhanh:<\/strong> N\u1ebfu vi\u1ec7c thay \u0111\u1ed5i DNS c\u1ea7n \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt g\u1ea7n nh\u01b0 t\u1ee9c th\u00ec (v\u00ed d\u1ee5: chuy\u1ec3n \u0111\u1ed5i sang m\u00e1y ch\u1ee7 d\u1ef1 ph\u00f2ng khi c\u00f3 s\u1ef1 c\u1ed1), TTL c\u1ef1c th\u1ea5p (60-300 gi\u00e2y) l\u00e0 c\u1ea7n thi\u1ebft.<\/li>\n<li><strong>Kh\u1ea3 n\u0103ng ch\u1ecbu t\u1ea3i c\u1ee7a m\u00e1y ch\u1ee7 DNS Authoritative:<\/strong> N\u1ebfu m\u00e1y ch\u1ee7 DNS c\u1ee7a b\u1ea1n c\u00f3 t\u00e0i nguy\u00ean h\u1ea1n ch\u1ebf ho\u1eb7c nh\u00e0 cung c\u1ea5p t\u00ednh ph\u00ed theo truy v\u1ea5n, b\u1ea1n c\u1ea7n c\u00e2n nh\u1eafc vi\u1ec7c s\u1eed d\u1ee5ng TTL cao h\u01a1n \u0111\u1ec3 gi\u1ea3m t\u1ea3i.<\/li>\n<li><strong>Lo\u1ea1i b\u1ea3n ghi:<\/strong> Nh\u01b0 \u0111\u00e3 \u0111\u1ec1 c\u1eadp, c\u00e1c lo\u1ea1i b\u1ea3n ghi kh\u00e1c nhau c\u00f3 th\u1ec3 c\u00f3 m\u1ee9c \u0111\u1ed9 \u01b0u ti\u00ean TTL kh\u00e1c nhau (v\u00ed d\u1ee5: TTL cho NS th\u01b0\u1eddng cao h\u01a1n nhi\u1ec1u so v\u1edbi A ho\u1eb7c MX).<\/li>\n<\/ol>\n<p>H\u00e3y c\u00e2n nh\u1eafc k\u1ef9 l\u01b0\u1ee1ng c\u00e1c y\u1ebfu t\u1ed1 tr\u00ean \u0111\u1ec3 \u0111\u01b0a ra quy\u1ebft \u0111\u1ecbnh ph\u00f9 h\u1ee3p nh\u1ea5t cho t\u1eebng b\u1ea3n ghi DNS c\u1ee7a b\u1ea1n, \u0111\u1ea3m b\u1ea3o s\u1ef1 c\u00e2n b\u1eb1ng gi\u1eefa t\u1ed1c \u0111\u1ed9 c\u1eadp nh\u1eadt, hi\u1ec7u su\u1ea5t v\u00e0 s\u1ef1 \u1ed5n \u0111\u1ecbnh.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Huong-dan-cach-kiem-tra-gia-tri-TTL-cua-ten-mien\"><\/span>H\u01b0\u1edbng d\u1eabn c\u00e1ch ki\u1ec3m tra gi\u00e1 tr\u1ecb TTL c\u1ee7a t\u00ean mi\u1ec1n<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Bi\u1ebft \u0111\u01b0\u1ee3c gi\u00e1 tr\u1ecb TTL hi\u1ec7n t\u1ea1i c\u1ee7a c\u00e1c b\u1ea3n ghi DNS l\u00e0 r\u1ea5t quan tr\u1ecdng, \u0111\u1eb7c bi\u1ec7t l\u00e0 tr\u01b0\u1edbc khi b\u1ea1n l\u00ean k\u1ebf ho\u1ea1ch th\u1ef1c hi\u1ec7n c\u00e1c thay \u0111\u1ed5i. C\u00f3 hai c\u00e1ch ch\u00ednh \u0111\u1ec3 ki\u1ec3m tra TTL: s\u1eed d\u1ee5ng c\u00f4ng c\u1ee5 tr\u1ef1c tuy\u1ebfn ho\u1eb7c d\u00f9ng d\u00f2ng l\u1ec7nh tr\u00ean m\u00e1y t\u00ednh c\u1ee7a b\u1ea1n.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-03.jpg\" alt=\"Time to live (TTL) 03\" width=\"750\" height=\"286\" class=\"aligncenter size-full wp-image-27825\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-03.jpg 750w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/05\/Time-to-live-TTL-03-300x114.jpg 300w\" sizes=\"auto, (max-width: 750px) 100vw, 750px\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Kiem-tra-TTL-bang-Cong-cu-Online-DNS-Checker-Tools\"><\/span>Ki\u1ec3m tra TTL b\u1eb1ng C\u00f4ng c\u1ee5 Online (DNS Checker Tools)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0110\u00e2y l\u00e0 c\u00e1ch \u0111\u01a1n gi\u1ea3n v\u00e0 tr\u1ef1c quan nh\u1ea5t, kh\u00f4ng y\u00eau c\u1ea7u ki\u1ebfn th\u1ee9c k\u1ef9 thu\u1eadt s\u00e2u. C\u00e1c c\u00f4ng c\u1ee5 n\u00e0y truy v\u1ea5n th\u00f4ng tin DNS t\u1eeb nhi\u1ec1u m\u00e1y ch\u1ee7 DNS resolver \u0111\u1eb7t t\u1ea1i c\u00e1c v\u1ecb tr\u00ed \u0111\u1ecba l\u00fd kh\u00e1c nhau tr\u00ean th\u1ebf gi\u1edbi.<\/p>\n<p>M\u1ed9t s\u1ed1 c\u00f4ng c\u1ee5 ph\u1ed5 bi\u1ebfn:<\/p>\n<ul>\n<li><strong>Google Admin Toolbox &#8211; Dig:<\/strong> (<a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/toolbox.googleapps.com\/apps\/dig\/\">https:\/\/toolbox.googleapps.com\/apps\/dig\/<\/a>) Giao di\u1ec7n \u0111\u01a1n gi\u1ea3n, nh\u1eadp t\u00ean mi\u1ec1n v\u00e0 ch\u1ecdn lo\u1ea1i b\u1ea3n ghi (A, MX, TXT, ANY&#8230;) \u0111\u1ec3 xem k\u1ebft qu\u1ea3.<\/li>\n<li><strong>DNSChecker.org:<\/strong> (<a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/dnschecker.org\/\">https:\/\/dnschecker.org\/<\/a>) Hi\u1ec3n th\u1ecb k\u1ebft qu\u1ea3 ki\u1ec3m tra t\u1eeb nhi\u1ec1u qu\u1ed1c gia, gi\u00fap b\u1ea1n h\u00ecnh dung qu\u00e1 tr\u00ecnh lan truy\u1ec1n DNS. Nh\u1eadp t\u00ean mi\u1ec1n, ch\u1ecdn lo\u1ea1i b\u1ea3n ghi v\u00e0 nh\u1ea5n Search.<\/li>\n<li><strong>whatsmydns.net:<\/strong> (<a target=\"_blank\" rel=\"noopener noreferrer\" href=\"https:\/\/www.whatsmydns.net\/\">https:\/\/www.whatsmydns.net\/<\/a>) T\u01b0\u01a1ng t\u1ef1 DNSChecker, cho ph\u00e9p ki\u1ec3m tra nhi\u1ec1u lo\u1ea1i b\u1ea3n ghi v\u00e0 xem k\u1ebft qu\u1ea3 t\u1eeb c\u00e1c \u0111\u1ecba \u0111i\u1ec3m kh\u00e1c nhau.<\/li>\n<\/ul>\n<p><strong>C\u00e1ch s\u1eed d\u1ee5ng c\u01a1 b\u1ea3n:<\/strong><\/p>\n<ol>\n<li>Truy c\u1eadp m\u1ed9t trong c\u00e1c website tr\u00ean.<\/li>\n<li>Nh\u1eadp t\u00ean mi\u1ec1n b\u1ea1n mu\u1ed1n ki\u1ec3m tra v\u00e0o \u00f4 t\u00ecm ki\u1ebfm.<\/li>\n<li>Ch\u1ecdn lo\u1ea1i b\u1ea3n ghi DNS b\u1ea1n quan t\u00e2m (v\u00ed d\u1ee5: A, MX, ho\u1eb7c \u0111\u1ec3 m\u1eb7c \u0111\u1ecbnh l\u00e0 A).<\/li>\n<li>Nh\u1ea5n n\u00fat &#8220;Search&#8221; ho\u1eb7c &#8220;Check&#8221;.<\/li>\n<li>K\u1ebft qu\u1ea3 s\u1ebd hi\u1ec3n th\u1ecb th\u00f4ng tin b\u1ea3n ghi (v\u00ed d\u1ee5: \u0111\u1ecba ch\u1ec9 IP) v\u00e0 gi\u00e1 tr\u1ecb TTL (th\u01b0\u1eddng l\u00e0 m\u1ed9t con s\u1ed1 \u0111\u1ee9ng tr\u01b0\u1edbc lo\u1ea1i b\u1ea3n ghi ho\u1eb7c trong m\u1ed9t c\u1ed9t ri\u00eang, \u0111\u01a1n v\u1ecb l\u00e0 gi\u00e2y). L\u01b0u \u00fd r\u1eb1ng c\u00e1c resolver kh\u00e1c nhau c\u00f3 th\u1ec3 hi\u1ec3n th\u1ecb TTL c\u00f2n l\u1ea1i kh\u00e1c nhau t\u00f9y thu\u1ed9c v\u00e0o th\u1eddi \u0111i\u1ec3m ch\u00fang cache l\u1ea7n cu\u1ed1i.<\/li>\n<\/ol>\n<h3><span class=\"ez-toc-section\" id=\"Kiem-tra-TTL-bang-Dong-lenh-Command-Line\"><\/span>Ki\u1ec3m tra TTL b\u1eb1ng D\u00f2ng l\u1ec7nh (Command Line)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>N\u1ebfu b\u1ea1n mu\u1ed1n ki\u1ec3m tra tr\u1ef1c ti\u1ebfp t\u1eeb m\u00e1y t\u00ednh c\u1ee7a m\u00ecnh ho\u1eb7c c\u1ea7n th\u00f4ng tin chi ti\u1ebft h\u01a1n, c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng c\u00e1c l\u1ec7nh trong Terminal (macOS\/Linux) ho\u1eb7c Command Prompt\/PowerShell (Windows).<\/p>\n<p><strong>Tr\u00ean Windows:<\/strong> S\u1eed d\u1ee5ng l\u1ec7nh <code>nslookup<\/code>.<\/p>\n<ol>\n<li>M\u1edf Command Prompt (g\u00f5 <code>cmd<\/code> v\u00e0o \u00f4 t\u00ecm ki\u1ebfm Windows).<\/li>\n<li>G\u00f5 <code>nslookup<\/code> v\u00e0 nh\u1ea5n Enter \u0111\u1ec3 v\u00e0o ch\u1ebf \u0111\u1ed9 t\u01b0\u01a1ng t\u00e1c.<\/li>\n<li>G\u00f5 <code>set querytype=ANY<\/code> (ho\u1eb7c <code>set type=A<\/code>, <code>set type=MX<\/code>&#8230;) v\u00e0 nh\u1ea5n Enter \u0111\u1ec3 ch\u1ec9 \u0111\u1ecbnh lo\u1ea1i b\u1ea3n ghi mu\u1ed1n xem.<\/li>\n<li>G\u00f5 t\u00ean mi\u1ec1n c\u1ea7n ki\u1ec3m tra (v\u00ed d\u1ee5: <code>google.com<\/code>) v\u00e0 nh\u1ea5n Enter.<\/li>\n<li>K\u1ebft qu\u1ea3 tr\u1ea3 v\u1ec1 s\u1ebd bao g\u1ed3m th\u00f4ng tin b\u1ea3n ghi v\u00e0 th\u01b0\u1eddng c\u00f3 d\u00f2ng <code>ttl = [s\u1ed1 gi\u00e2y]<\/code> ho\u1eb7c hi\u1ec3n th\u1ecb TTL ngay sau t\u00ean mi\u1ec1n trong ph\u1ea7n tr\u1ea3 l\u1eddi t\u1eeb m\u00e1y ch\u1ee7 DNS.<\/li>\n<\/ol>\n<p><i>L\u01b0u \u00fd:<\/i> <code>nslookup<\/code> tr\u00ean Windows \u0111\u00f4i khi kh\u00f4ng hi\u1ec3n th\u1ecb TTL m\u1ed9t c\u00e1ch r\u00f5 r\u00e0ng cho t\u1ea5t c\u1ea3 c\u00e1c lo\u1ea1i b\u1ea3n ghi.<\/p>\n<p><strong>Tr\u00ean macOS ho\u1eb7c Linux:<\/strong> S\u1eed d\u1ee5ng l\u1ec7nh <code>dig<\/code> (m\u1ea1nh m\u1ebd v\u00e0 chi ti\u1ebft h\u01a1n <code>nslookup<\/code>).<\/p>\n<ol>\n<li>M\u1edf Terminal.<\/li>\n<li>G\u00f5 l\u1ec7nh <code>dig tenmien.com<\/code> (thay <code>tenmien.com<\/code> b\u1eb1ng t\u00ean mi\u1ec1n b\u1ea1n mu\u1ed1n ki\u1ec3m tra). M\u1eb7c \u0111\u1ecbnh <code>dig<\/code> s\u1ebd ki\u1ec3m tra b\u1ea3n ghi A.<\/li>\n<li>\u0110\u1ec3 ki\u1ec3m tra lo\u1ea1i b\u1ea3n ghi kh\u00e1c, th\u00eam lo\u1ea1i v\u00e0o sau t\u00ean mi\u1ec1n: <code>dig tenmien.com MX<\/code>, <code>dig tenmien.com TXT<\/code>, <code>dig tenmien.com ANY<\/code>.<\/li>\n<li>Trong k\u1ebft qu\u1ea3 tr\u1ea3 v\u1ec1 (ph\u1ea7n <code>ANSWER SECTION<\/code>), b\u1ea1n s\u1ebd th\u1ea5y m\u1ed9t con s\u1ed1 \u0111\u1ee9ng gi\u1eefa t\u00ean mi\u1ec1n v\u00e0 lo\u1ea1i b\u1ea3n ghi. \u0110\u00f3 ch\u00ednh l\u00e0 gi\u00e1 tr\u1ecb TTL t\u00ednh b\u1eb1ng gi\u00e2y.<\/li>\n<\/ol>\n<p>V\u00ed d\u1ee5 output c\u1ee7a <code>dig<\/code>: <code>vidu.com. 3600 IN A 192.0.2.1<\/code> \u1ede \u0111\u00e2y, <code>3600<\/code> ch\u00ednh l\u00e0 gi\u00e1 tr\u1ecb TTL.<\/p>\n<p>S\u1eed d\u1ee5ng d\u00f2ng l\u1ec7nh cho ph\u00e9p b\u1ea1n th\u1ea5y \u0111\u01b0\u1ee3c TTL m\u00e0 m\u00e1y ch\u1ee7 DNS resolver b\u1ea1n \u0111ang d\u00f9ng nh\u00ecn th\u1ea5y.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Luu-y-quan-trong-khi-Thay-doi-gia-tri-TTL\"><\/span>L\u01b0u \u00fd quan tr\u1ecdng khi Thay \u0111\u1ed5i gi\u00e1 tr\u1ecb TTL<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Vi\u1ec7c thay \u0111\u1ed5i TTL l\u00e0 m\u1ed9t c\u00f4ng c\u1ee5 m\u1ea1nh m\u1ebd, nh\u01b0ng c\u1ea7n th\u1ef1c hi\u1ec7n c\u1ea9n th\u1eadn \u0111\u1ec3 tr\u00e1nh g\u00e2y gi\u00e1n \u0111o\u1ea1n d\u1ecbch v\u1ee5 kh\u00f4ng mong mu\u1ed1n. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 nh\u1eefng \u0111i\u1ec3m c\u1ea7n l\u01b0u \u00fd.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Nen-giam-TTL-truoc-khi-thuc-hien-thay-doi-DNS-quan-trong\"><\/span>N\u00ean gi\u1ea3m TTL tr\u01b0\u1edbc khi th\u1ef1c hi\u1ec7n thay \u0111\u1ed5i DNS quan tr\u1ecdng<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0110\u00e2y l\u00e0 m\u1ed9t th\u1ef1c h\u00e0nh t\u1ed1t nh\u1ea5t (best practice) \u0111\u01b0\u1ee3c khuy\u1ebfn ngh\u1ecb r\u1ed9ng r\u00e3i. Tr\u01b0\u1edbc khi b\u1ea1n th\u1ef1c hi\u1ec7n b\u1ea5t k\u1ef3 thay \u0111\u1ed5i DNS l\u1edbn n\u00e0o (\u0111\u1ed5i IP m\u00e1y ch\u1ee7 web, chuy\u1ec3n \u0111\u1ed5i nh\u00e0 cung c\u1ea5p email, thay \u0111\u1ed5i m\u00e1y ch\u1ee7 NS), h\u00e3y ch\u1ee7 \u0111\u1ed9ng gi\u1ea3m gi\u00e1 tr\u1ecb TTL c\u1ee7a c\u00e1c b\u1ea3n ghi li\u00ean quan xu\u1ed1ng m\u1ee9c th\u1ea5p.<\/p>\n<p>M\u1ee9c th\u1ea5p th\u01b0\u1eddng l\u00e0 t\u1eeb 60 gi\u00e2y (1 ph\u00fat) \u0111\u1ebfn 300 gi\u00e2y (5 ph\u00fat).<\/p>\n<p>Quan tr\u1ecdng l\u00e0 b\u1ea1n ph\u1ea3i th\u1ef1c hi\u1ec7n vi\u1ec7c gi\u1ea3m TTL n\u00e0y <strong>\u00edt nh\u1ea5t m\u1ed9t kho\u1ea3ng th\u1eddi gian b\u1eb1ng gi\u00e1 tr\u1ecb TTL c\u0169 tr\u01b0\u1edbc \u0111\u00f3<\/strong>. V\u00ed d\u1ee5, n\u1ebfu TTL hi\u1ec7n t\u1ea1i l\u00e0 86400 gi\u00e2y (24 gi\u1edd), b\u1ea1n n\u00ean gi\u1ea3m TTL xu\u1ed1ng 300 gi\u00e2y v\u00e0 ch\u1edd \u00edt nh\u1ea5t 24 gi\u1edd \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o t\u1ea5t c\u1ea3 c\u00e1c resolver tr\u00ean th\u1ebf gi\u1edbi \u0111\u00e3 nh\u1eadn \u0111\u01b0\u1ee3c gi\u00e1 tr\u1ecb TTL th\u1ea5p m\u1edbi n\u00e0y.<\/p>\n<p>Sau khi th\u1eddi gian ch\u1edd k\u1ebft th\u00fac, b\u1ea1n m\u1edbi ti\u1ebfn h\u00e0nh thay \u0111\u1ed5i b\u1ea3n ghi DNS th\u1ef1c t\u1ebf (v\u00ed d\u1ee5: c\u1eadp nh\u1eadt \u0111\u1ecba ch\u1ec9 IP m\u1edbi). Nh\u1edd TTL \u0111\u00e3 \u0111\u01b0\u1ee3c gi\u1ea3m tr\u01b0\u1edbc \u0111\u00f3, thay \u0111\u1ed5i m\u1edbi n\u00e0y s\u1ebd lan truy\u1ec1n r\u1ea5t nhanh ch\u00f3ng, gi\u1ea3m thi\u1ec3u th\u1eddi gian gi\u00e1n \u0111o\u1ea1n ho\u1eb7c truy c\u1eadp v\u00e0o th\u00f4ng tin c\u0169.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Thoi-gian-cho-sau-khi-thay-doi-TTL\"><\/span>Th\u1eddi gian ch\u1edd sau khi thay \u0111\u1ed5i TTL<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>M\u1ed9t \u0111i\u1ec3m d\u1ec5 g\u00e2y nh\u1ea7m l\u1eabn l\u00e0 vi\u1ec7c thay \u0111\u1ed5i ch\u00ednh gi\u00e1 tr\u1ecb TTL c\u0169ng c\u1ea7n th\u1eddi gian \u0111\u1ec3 lan truy\u1ec1n. Khi b\u1ea1n thay \u0111\u1ed5i TTL t\u1eeb 86400 xu\u1ed1ng 300, c\u00e1c m\u00e1y ch\u1ee7 resolver s\u1ebd kh\u00f4ng c\u1eadp nh\u1eadt gi\u00e1 tr\u1ecb TTL m\u1edbi n\u00e0y ngay l\u1eadp t\u1ee9c.<\/p>\n<p>Ch\u00fang v\u1eabn gi\u1eef gi\u00e1 tr\u1ecb TTL c\u0169 (86400) cho \u0111\u1ebfn khi cache hi\u1ec7n t\u1ea1i c\u1ee7a ch\u00fang h\u1ebft h\u1ea1n. Ch\u1ec9 sau khi cache c\u0169 h\u1ebft h\u1ea1n v\u00e0 ch\u00fang truy v\u1ea5n l\u1ea1i m\u00e1y ch\u1ee7 authoritative, ch\u00fang m\u1edbi nh\u1eadn \u0111\u01b0\u1ee3c gi\u00e1 tr\u1ecb TTL m\u1edbi (300).<\/p>\n<p>\u0110\u00e2y l\u00e0 l\u00fd do t\u1ea1i sao b\u1ea1n c\u1ea7n ph\u1ea3i ch\u1edd m\u1ed9t kho\u1ea3ng th\u1eddi gian b\u1eb1ng gi\u00e1 tr\u1ecb TTL c\u0169 sau khi gi\u1ea3m TTL, tr\u01b0\u1edbc khi th\u1ef1c hi\u1ec7n thay \u0111\u1ed5i DNS ti\u1ebfp theo. Vi\u1ec7c n\u00f3ng v\u1ed9i thay \u0111\u1ed5i ngay l\u1eadp t\u1ee9c c\u00f3 th\u1ec3 kh\u00f4ng mang l\u1ea1i hi\u1ec7u qu\u1ea3 t\u0103ng t\u1ed1c lan truy\u1ec1n nh\u01b0 mong \u0111\u1ee3i.<\/p>\n<p>H\u00e3y lu\u00f4n ki\u00ean nh\u1eabn v\u00e0 t\u00ednh to\u00e1n th\u1eddi gian ch\u1edd h\u1ee3p l\u00fd d\u1ef1a tr\u00ean gi\u00e1 tr\u1ecb TTL c\u0169 khi th\u1ef1c hi\u1ec7n c\u00e1c thay \u0111\u1ed5i li\u00ean quan \u0111\u1ebfn DNS v\u00e0 TTL.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cau-hoi-thuong-gap-ve-TTL-FAQ\"><\/span>C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p v\u1ec1 TTL (FAQ)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>D\u01b0\u1edbi \u0111\u00e2y l\u00e0 m\u1ed9t s\u1ed1 c\u00e2u h\u1ecfi ph\u1ed5 bi\u1ebfn v\u00e0 c\u00e2u tr\u1ea3 l\u1eddi ng\u1eafn g\u1ecdn v\u1ec1 Time To Live:<\/p>\n<h3><span class=\"ez-toc-section\" id=\"TTL-1-giay-co-y-nghia-gi\"><\/span>TTL 1 gi\u00e2y c\u00f3 \u00fd ngh\u0129a g\u00ec?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>TTL 1 gi\u00e2y v\u1ec1 m\u1eb7t l\u00fd thuy\u1ebft c\u00f3 ngh\u0129a l\u00e0 th\u00f4ng tin DNS ch\u1ec9 \u0111\u01b0\u1ee3c cache trong 1 gi\u00e2y. \u0110i\u1ec1u n\u00e0y bu\u1ed9c c\u00e1c resolver ph\u1ea3i h\u1ecfi l\u1ea1i m\u00e1y ch\u1ee7 authoritative g\u1ea7n nh\u01b0 li\u00ean t\u1ee5c. M\u1eb7c d\u00f9 gi\u00fap c\u1eadp nh\u1eadt c\u1ef1c nhanh, TTL 1 th\u01b0\u1eddng kh\u00f4ng \u0111\u01b0\u1ee3c khuy\u1ebfn kh\u00edch v\u00ec t\u1ea1o ra t\u1ea3i r\u1ea5t l\u1edbn cho m\u00e1y ch\u1ee7 DNS v\u00e0 c\u00f3 th\u1ec3 b\u1ecb m\u1ed9t s\u1ed1 resolver b\u1ecf qua (coi l\u00e0 qu\u00e1 th\u1ea5p).<\/p>\n<h3><span class=\"ez-toc-section\" id=\"TTL-300-5-phut-co-tot-khong\"><\/span>TTL 300 (5 ph\u00fat) c\u00f3 t\u1ed1t kh\u00f4ng?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>TTL 300 gi\u00e2y (5 ph\u00fat) \u0111\u01b0\u1ee3c coi l\u00e0 m\u1ed9t gi\u00e1 tr\u1ecb TTL th\u1ea5p, th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng t\u1ea1m th\u1eddi khi chu\u1ea9n b\u1ecb ho\u1eb7c \u0111ang th\u1ef1c hi\u1ec7n c\u00e1c thay \u0111\u1ed5i DNS quan tr\u1ecdng. M\u1ee9c n\u00e0y c\u00e2n b\u1eb1ng kh\u00e1 t\u1ed1t gi\u1eefa vi\u1ec7c \u0111\u1ea3m b\u1ea3o c\u1eadp nh\u1eadt t\u01b0\u01a1ng \u0111\u1ed1i nhanh v\u00e0 kh\u00f4ng g\u00e2y qu\u00e1 t\u1ea3i nghi\u00eam tr\u1ecdng cho m\u00e1y ch\u1ee7 authoritative trong th\u1eddi gian ng\u1eafn.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"TTL-va-Ping-khac-nhau-nhu-the-nao\"><\/span>TTL v\u00e0 Ping kh\u00e1c nhau nh\u01b0 th\u1ebf n\u00e0o?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>TTL v\u00e0 Ping l\u00e0 hai kh\u00e1i ni\u1ec7m kh\u00e1c nhau. TTL trong DNS l\u00e0 th\u1eddi gian cache b\u1ea3n ghi. C\u00f2n TTL trong k\u1ebft qu\u1ea3 l\u1ec7nh <code>ping<\/code> (v\u00ed d\u1ee5: <code>TTL=64<\/code>, <code>TTL=128<\/code>) l\u00e0 m\u1ed9t gi\u00e1 tr\u1ecb trong g\u00f3i tin IP, ch\u1ec9 s\u1ed1 b\u01b0\u1edbc nh\u1ea3y (hop) t\u1ed1i \u0111a m\u00e0 g\u00f3i tin \u0111\u01b0\u1ee3c ph\u00e9p \u0111i qua trong m\u1ea1ng tr\u01b0\u1edbc khi b\u1ecb h\u1ee7y. Ch\u00fang kh\u00f4ng li\u00ean quan tr\u1ef1c ti\u1ebfp.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Thay-doi-TTL-co-lam-website-bi-gian-doan-downtime-khong\"><\/span>Thay \u0111\u1ed5i TTL c\u00f3 l\u00e0m website b\u1ecb gi\u00e1n \u0111o\u1ea1n (downtime) kh\u00f4ng?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>B\u1ea3n th\u00e2n vi\u1ec7c thay \u0111\u1ed5i gi\u00e1 tr\u1ecb TTL kh\u00f4ng g\u00e2y ra downtime. Tuy nhi\u00ean, vi\u1ec7c c\u1ea5u h\u00ecnh TTL kh\u00f4ng h\u1ee3p l\u00fd (v\u00ed d\u1ee5: TTL qu\u00e1 cao khi \u0111ang c\u1ea7n thay \u0111\u1ed5i IP g\u1ea5p) c\u00f3 th\u1ec3 k\u00e9o d\u00e0i th\u1eddi gian ng\u01b0\u1eddi d\u00f9ng truy c\u1eadp v\u00e0o \u0111\u1ecba ch\u1ec9 IP c\u0169, d\u1eabn \u0111\u1ebfn c\u1ea3m gi\u00e1c website b\u1ecb l\u1ed7i ho\u1eb7c gi\u00e1n \u0111o\u1ea1n. Gi\u1ea3m TTL \u0111\u00fang c\u00e1ch tr\u01b0\u1edbc khi thay \u0111\u1ed5i gi\u00fap h\u1ea1n ch\u1ebf \u0111i\u1ec1u n\u00e0y.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Nha-cung-cap-hostingten-mien-cua-toi-dat-TTL-mac-dinh-la-bao-nhieu\"><\/span>Nh\u00e0 cung c\u1ea5p hosting\/t\u00ean mi\u1ec1n c\u1ee7a t\u00f4i \u0111\u1eb7t TTL m\u1eb7c \u0111\u1ecbnh l\u00e0 bao nhi\u00eau?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Gi\u00e1 tr\u1ecb TTL m\u1eb7c \u0111\u1ecbnh kh\u00e1c nhau t\u00f9y theo nh\u00e0 cung c\u1ea5p. C\u00e1ch t\u1ed1t nh\u1ea5t l\u00e0 ki\u1ec3m tra t\u00e0i li\u1ec7u h\u01b0\u1edbng d\u1eabn c\u1ee7a h\u1ecd ho\u1eb7c xem tr\u1ef1c ti\u1ebfp trong b\u1ea3ng \u0111i\u1ec1u khi\u1ec3n DNS m\u00e0 h\u1ecd cung c\u1ea5p. Th\u00f4ng th\u01b0\u1eddng, c\u00e1c gi\u00e1 tr\u1ecb m\u1eb7c \u0111\u1ecbnh n\u1eb1m trong kho\u1ea3ng 3600 \u0111\u1ebfn 14400 gi\u00e2y.<\/p>\n<p>Hi\u1ec3u r\u00f5 v\u00e0 qu\u1ea3n l\u00fd hi\u1ec7u qu\u1ea3 Time To Live l\u00e0 m\u1ed9t k\u1ef9 n\u0103ng c\u1ea7n thi\u1ebft cho b\u1ea5t k\u1ef3 ai l\u00e0m vi\u1ec7c v\u1edbi website v\u00e0 t\u00ean mi\u1ec1n. B\u1eb1ng c\u00e1ch c\u1ea5u h\u00ecnh TTL ph\u00f9 h\u1ee3p, b\u1ea1n c\u00f3 th\u1ec3 \u0111\u1ea3m b\u1ea3o h\u1ec7 th\u1ed1ng DNS ho\u1ea1t \u0111\u1ed9ng \u1ed5n \u0111\u1ecbnh, c\u00e1c thay \u0111\u1ed5i \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt nhanh ch\u00f3ng v\u00e0 mang l\u1ea1i tr\u1ea3i nghi\u1ec7m t\u1ed1t nh\u1ea5t cho ng\u01b0\u1eddi d\u00f9ng.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>TTL (Time To Live) l\u00e0 m\u1ed9t gi\u00e1 tr\u1ecb c\u00e0i \u0111\u1eb7t cho bi\u1ebft kho\u1ea3ng th\u1eddi gian m\u1ed9t b\u1ea3n ghi DNS \u0111\u01b0\u1ee3c ph\u00e9p l\u01b0u tr\u1eef trong b\u1ed9 nh\u1edb \u0111\u1ec7m (cache). Th\u00f4ng s\u1ed1 n\u00e0y r\u1ea5t quan tr\u1ecdng cho vi\u1ec7c qu\u1ea3n l\u00fd t\u00ean mi\u1ec1n v\u00e0 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 c\u1eadp nh\u1eadt th\u00f4ng tin DNS c\u1ee7a website b\u1ea1n. Hi\u1ec3u<\/p>\n","protected":false},"author":2,"featured_media":27826,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-27822","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-hosting"],"_links":{"self":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts\/27822","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/comments?post=27822"}],"version-history":[{"count":1,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts\/27822\/revisions"}],"predecessor-version":[{"id":27827,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts\/27822\/revisions\/27827"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/media\/27826"}],"wp:attachment":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/media?parent=27822"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/categories?post=27822"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/tags?post=27822"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}