瀏覽器會隱藏 www 子網域，www 子網域看起來會跟沒有 www 的根網域一模一樣。所以使用 www 子網域的時候應該要確保輸入根網域的時候也會重新導向到 www，才不會讓使用者輸入網址時不知道為何無法載入。
例如：架站服務 Netlify 預設指派 www 子網域給網站的時候會同時指派根網域。
If you assign an apex domain or a www subdomain to your site, Netlify will automatically add both the apex domain and the www subdomain.
— https://docs.netlify.com/domains-https/custom-domains/configure-external-dns/
以下是有 www 子網域但是造訪根網域時會除錯的常用臺灣網站，依 Tranco 排行排序。
最近更新：2023-04-14T11:43:16.603Z
這些網站有 www 子網域，瀏覽器上看起來像是沒有 www，但是照瀏覽器上所顯示的輸入時會出錯。
| Tranco 排行 | 網站 | |
|---|---|---|
| #11276 | ||
| #11534 | ||
| #12307 | ||
| #12791 | ||
| #12918 | ||
| #13508 | ||
| #13734 | ||
| #15023 | ||
| #15001 | ||
| #14963 | ||
| #16329 | ||
| #16864 | ||
| #17048 | ||
| #18665 | ||
| #19296 | ||
| #20701 | ||
| #20655 | ||
| #21077 | ||
| #21830 | ||
| #23164 | ||
| #23902 | ||
| #23980 | ||
| #24886 | ||
| #30693 | ||
| #31521 | ||
| #32925 | ||
| #33559 | ||
| #34293 | ||
| #36872 | ||
| #37615 | ||
| #38341 | ||
| #39294 | ||
| #40273 | ||
| #40439 | ||
| #42868 | ||
| #43193 | ||
| #43606 | ||
| #46037 | ||
| #49194 | ||
| #48885 | ||
| #49588 | ||
| #50894 | ||
| #50014 | ||
| #52509 | ||
| #54827 | ||
| #56455 | ||
| #57024 | ||
| #58086 | ||
| #58288 | ||
| #59458 | ||
| #59325 | ||
| #60519 | ||
| #60887 | ||
| #61402 | ||
| #62414 | ||
| #64188 | ||
| #64979 | ||
| #65699 | ||
| #66025 | ||
| #68474 | ||
| #68637 | ||
| #70563 | ||
| #70425 | ||
| #71012 | ||
| #70880 | ||
| #71548 | ||
| #71620 | ||
| #71911 | ||
| #74250 | ||
| #75343 | ||
| #75771 | ||
| #76014 | ||
| #75916 | ||
| #78591 | ||
| #79814 | ||
| #80217 | ||
| #83393 | ||
| #84341 | ||
| #84190 | ||
| #84473 | ||
| #84862 | ||
| #85055 | ||
| #85428 | ||
| #85821 | ||
| #86273 | ||
| #87515 | ||
| #87817 | ||
| #88124 | ||
| #90100 | ||
| #90468 | ||
| #90940 | ||
| #91817 | ||
| #91352 | ||
| #92505 | ||
| #92395 | ||
| #92968 | ||
| #93773 | ||
| #94170 | ||
| #94952 | ||
| #94428 | ||
| #95651 | ||
| #96189 | ||
| #97501 | ||
| #96612 | ||
| #98616 | ||
| #100836 | ||
| #100412 | ||
| #101510 | ||
| #102092 | ||
| #104289 | ||
| #104656 | ||
| #105837 | ||
| #106929 | ||
| #108269 | ||
| #109954 | ||
| #111308 | ||
| #109434 | ||
| #112734 | ||
| #112868 | ||
| #120074 | ||
| #124152 | ||
| #123030 | ||
| #127665 | ||
| #128177 | ||
| #129950 | ||
| #131958 | ||
| #132648 | ||
| #133048 | ||
| #135280 | ||
| #135002 | ||
| #138934 | ||
| #140777 | ||
| #142944 | ||
| #143557 | ||
| #143999 | ||
| #145409 | ||
| #150513 | ||
| #152349 | ||
| #158303 | ||
| #158660 | ||
| #159322 | ||
| #159545 | ||
| #163262 | ||
| #165444 | ||
| #166876 | ||
| #171707 | ||
| #174391 | ||
| #174884 | ||
| #176739 | ||
| #178140 | ||
| #183189 | ||
| #183692 | ||
| #188050 | ||
| #189335 | ||
| #190313 | ||
| #192178 | ||
| #194312 | ||
| #194138 | ||
| #195871 | ||
| #197294 | ||
| #200599 | ||
| #203138 | ||
| #206670 | ||
| #211500 | ||
| #211629 | ||
| #211674 | ||
| #213530 | ||
| #212984 | ||
| #215349 | ||
| #215561 | ||
| #216585 | ||
| #219162 | ||
| #218633 | ||
| #223588 | ||
| #223982 | ||
| #227611 | ||
| #229722 | ||
| #231110 | ||
| #230736 | ||
| #231028 | ||
| #235007 | ||
| #235602 | ||
| #235733 | ||
| #239921 | ||
| #238954 | ||
| #242139 | ||
| #245284 | ||
| #245898 | ||
| #246928 | ||
| #246361 | ||
| #245903 | ||
| #249276 | ||
| #249559 | ||
| #254236 | ||
| #257850 | ||
| #262095 | ||
| #262882 | ||
| #263302 | ||
| #264992 | ||
| #266092 | ||
| #269215 | ||
| #271349 | ||
| #273693 | ||
| #271891 | ||
| #277974 | ||
| #278454 | ||
| #279131 | ||
| #279323 | ||
| #279426 | ||
| #280160 | ||
| #280840 | ||
| #281009 | ||
| #280968 | ||
| #281688 | ||
| #286218 | ||
| #286175 | ||
| #288055 | ||
| #289617 | ||
| #290940 | ||
| #293940 | ||
| #298891 | ||
| #299471 | ||
| #301937 | ||
| #305524 | ||
| #306030 | ||
| #306013 | ||
| #307543 | ||
| #308105 | ||
| #308529 | ||
| #317059 | ||
| #318785 | ||
| #319728 | ||
| #320396 | ||
| #323375 | ||
| #325049 | ||
| #326718 | ||
| #326901 | ||
| #328697 | ||
| #329573 | ||
| #334020 | ||
| #332247 | ||
| #335272 | ||
| #335840 | ||
| #342095 | ||
| #343985 | ||
| #343818 | ||
| #344800 | ||
| #348748 | ||
| #349912 | ||
| #350698 | ||
| #352340 | ||
| #354427 | ||
| #355883 | ||
| #356485 | ||
| #361676 | ||
| #362006 | ||
| #367623 | ||
| #366661 | ||
| #369926 | ||
| #375108 | ||
| #376948 | ||
| #376929 | ||
| #376983 | ||
| #380083 | ||
| #380148 | ||
| #380751 | ||
| #382660 | ||
| #381668 | ||
| #386935 | ||
| #385984 | ||
| #388174 | ||
| #389907 | ||
| #393023 | ||
| #395518 | ||
| #398921 | ||
| #398979 | ||
| #401016 | ||
| #401478 | ||
| #402952 | ||
| #405404 | ||
| #407939 | ||
| #411067 | ||
| #412513 | ||
| #416867 | ||
| #416084 | ||
| #419254 | ||
| #419369 | ||
| #423330 | ||
| #423900 | ||
| #425405 | ||
| #427672 | ||
| #428336 | ||
| #428515 | ||
| #430222 | ||
| #435510 | ||
| #436360 | ||
| #436916 | ||
| #438607 | ||
| #439137 | ||
| #440000 | ||
| #441349 | ||
| #441999 | ||
| #444652 | ||
| #446255 | ||
| #447479 | ||
| #448498 | ||
| #456014 | ||
| #459297 | ||
| #457981 | ||
| #462194 | ||
| #464260 | ||
| #465944 | ||
| #467443 | ||
| #467458 | ||
| #469644 | ||
| #467751 | ||
| #472729 | ||
| #474781 | ||
| #477379 | ||
| #476647 | ||
| #477936 | ||
| #480100 | ||
| #481325 | ||
| #481300 | ||
| #488816 | ||
| #488881 | ||
| #492574 | ||
| #496071 | ||
| #496461 | ||
| #499002 | ||
| #501232 | ||
| #501348 | ||
| #506129 | ||
| #509916 | ||
| #510554 | ||
| #510702 | ||
| #510851 | ||
| #510922 | ||
| #511023 | ||
| #511031 | ||
| #511098 | ||
| #511111 | ||
| #511182 | ||
| #511471 | ||
| #516252 | ||
| #517100 | ||
| #517689 | ||
| #524558 | ||
| #527031 | ||
| #530562 | ||
| #534551 | ||
| #534636 | ||
| #536887 | ||
| #537898 | ||
| #539288 | ||
| #539384 | ||
| #540564 | ||
| #544422 | ||
| #543162 | ||
| #548669 | ||
| #548944 | ||
| #549393 | ||
| #550630 | ||
| #551744 | ||
| #551764 | ||
| #551797 | ||
| #551905 | ||
| #552584 | ||
| #557698 | ||
| #561073 | ||
| #563023 | ||
| #565145 | ||
| #563104 | ||
| #565806 | ||
| #566028 | ||
| #566065 | ||
| #566101 | ||
| #566152 | ||
| #571312 | ||
| #573097 | ||
| #579851 | ||
| #581740 | ||
| #581853 | ||
| #585496 | ||
| #585695 | ||
| #585753 | ||
| #585789 | ||
| #585861 | ||
| #585864 | ||
| #586039 | ||
| #589848 | ||
| #595538 | ||
| #600898 | ||
| #599290 | ||
| #604144 | ||
| #605354 | ||
| #605520 | ||
| #606480 | ||
| #613915 | ||
| #615320 | ||
| #618480 | ||
| #617837 | ||
| #620557 | ||
| #620784 | ||
| #620822 | ||
| #620876 | ||
| #621064 | ||
| #621086 | ||
| #621139 | ||
| #621279 | ||
| #621793 | ||
| #623950 | ||
| #629689 | ||
| #630131 | ||
| #637035 | ||
| #637098 | ||
| #639717 | ||
| #640079 | ||
| #642788 | ||
| #646561 | ||
| #647900 | ||
| #649119 | ||
| #654460 | ||
| #658005 | ||
| #664159 | ||
| #665546 | ||
| #669968 | ||
| #670727 | ||
| #682830 | ||
| #685425 | ||
| #687663 | ||
| #687698 | ||
| #687729 | ||
| #687899 | ||
| #687920 | ||
| #687983 | ||
| #687996 | ||
| #688012 | ||
| #688049 | ||
| #688094 | ||
| #688127 | ||
| #688120 | ||
| #688190 | ||
| #688204 | ||
| #688379 | ||
| #688435 | ||
| #688471 | ||
| #688543 | ||
| #688588 | ||
| #688614 | ||
| #688630 | ||
| #691213 | ||
| #693702 | ||
| #701790 | ||
| #703754 | ||
| #706462 | ||
| #713321 | ||
| #712361 | ||
| #715668 | ||
| #717581 | ||
| #722835 | ||
| #726642 | ||
| #726092 | ||
| #726878 | ||
| #727585 | ||
| #728147 | ||
| #732285 | ||
| #735732 | ||
| #737701 | ||
| #740859 | ||
| #743847 | ||
| #743922 | ||
| #744081 | ||
| #744079 | ||
| #744109 | ||
| #744117 | ||
| #744269 | ||
| #744279 | ||
| #744302 | ||
| #744374 | ||
| #744384 | ||
| #744410 | ||
| #744444 | ||
| #744495 | ||
| #744478 | ||
| #744670 | ||
| #744745 | ||
| #744760 | ||
| #744772 | ||
| #744967 | ||
| #744933 | ||
| #745056 | ||
| #745211 | ||
| #745337 | ||
| #745364 | ||
| #745451 | ||
| #745494 | ||
| #745511 | ||
| #745505 | ||
| #745521 | ||
| #745544 | ||
| #745626 | ||
| #745642 | ||
| #745704 | ||
| #746333 | ||
| #752145 | ||
| #754789 | ||
| #756893 | ||
| #761335 | ||
| #771938 | ||
| #786161 | ||
| #786846 | ||
| #782735 | ||
| #795978 | ||
| #795403 | ||
| #796795 | ||
| #804715 | ||
| #807823 | ||
| #816185 | ||
| #815596 | ||
| #817017 | ||
| #825024 | ||
| #829773 | ||
| #830551 | ||
| #835198 | ||
| #849303 | ||
| #848432 | ||
| #849878 | ||
| #852152 | ||
| #853559 | ||
| #857848 | ||
| #855143 | ||
| #866608 | ||
| #866809 | ||
| #867223 | ||
| #871338 | ||
| #871679 | ||
| #875680 | ||
| #875406 | ||
| #880878 | ||
| #887129 | ||
| #887500 | ||
| #891998 | ||
| #893526 | ||
| #894391 | ||
| #893798 | ||
| #894665 | ||
| #896897 | ||
| #912722 | ||
| #914470 | ||
| #921540 | ||
| #921956 | ||
| #927001 | ||
| #929849 | ||
| #929946 | ||
| #929883 | ||
| #930109 | ||
| #930262 | ||
| #930387 | ||
| #930436 | ||
| #930484 | ||
| #930830 | ||
| #930784 | ||
| #931004 | ||
| #931069 | ||
| #931193 | ||
| #931266 | ||
| #931255 | ||
| #931485 | ||
| #931591 | ||
| #931621 | ||
| #931615 | ||
| #931635 | ||
| #931770 | ||
| #931791 | ||
| #931970 | ||
| #932056 | ||
| #932201 | ||
| #932304 | ||
| #932310 | ||
| #932329 | ||
| #932420 | ||
| #932536 | ||
| #932605 | ||
| #932632 | ||
| #932669 | ||
| #932926 | ||
| #933012 | ||
| #933103 | ||
| #933196 | ||
| #933223 | ||
| #933307 | ||
| #933495 | ||
| #933520 | ||
| #933538 | ||
| #933594 | ||
| #933667 | ||
| #933833 | ||
| #934037 | ||
| #934067 | ||
| #934239 | ||
| #934205 | ||
| #934330 | ||
| #934423 | ||
| #934384 | ||
| #934472 | ||
| #934791 | ||
| #934909 | ||
| #935050 | ||
| #935041 | ||
| #935137 | ||
| #935133 | ||
| #935295 | ||
| #935458 | ||
| #935511 | ||
| #935505 | ||
| #935522 | ||
| #935556 | ||
| #935551 | ||
| #935559 | ||
| #935631 | ||
| #935774 | ||
| #935863 | ||
| #936012 | ||
| #936097 | ||
| #936113 | ||
| #936191 | ||
| #936197 | ||
| #936267 | ||
| #936358 | ||
| #936479 | ||
| #936482 | ||
| #936498 | ||
| #936556 | ||
| #936633 | ||
| #936713 | ||
| #936689 | ||
| #936743 | ||
| #937271 | ||
| #937309 | ||
| #937351 | ||
| #937451 | ||
| #940885 | ||
| #939931 | ||
| #944554 | ||
| #943908 | ||
| #956865 | ||
| #952843 | ||
| #959510 | ||
| #965074 | ||
| #969877 | ||
| #967352 | ||
| #973203 | ||
| #973642 | ||
| #972095 | ||
| #976286 | ||
| #975938 | ||
| #977988 | ||
| #985093 | ||
| #984417 | ||
| #991390 | ||
| #990374 | ||
| #989278 | ||
| #998882 |
Cloudflare 說明文件：DNS record types
若主要使用的網址是 www.example.com，要讓 example.com 重新導向到主網址：
如果 DNS 提供者像 Cloudflare 一樣支援 CNAME flattening，可以直接新增一個 CNAME 紀錄：
@www.example.comCNAME 紀錄一般無法用於根網域，此時可以自行複製 www 子網域的 A 紀錄，例如 www 指向 0.0.0.0 時只要再建立一個 A 紀錄： 便會
@0.0.0.0造訪 example.com 時便會跟 www.example.com 時解析成同一個 IP 位址。
之後再從伺服器回傳 302 或 307 重新導向到主網址。
作：如月飛羽；設計參考 Why No HTTPS.