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：2024-03-16T08:05:00.291Z
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 | |
|---|---|---|
| #8333 | ||
| #12787 | ||
| #17178 | ||
| #17464 | ||
| #20579 | ||
| #22309 | ||
| #23693 | ||
| #25408 | ||
| #24568 | ||
| #27019 | ||
| #28140 | ||
| #30091 | ||
| #30278 | ||
| #30670 | ||
| #30438 | ||
| #31586 | ||
| #32692 | ||
| #33726 | ||
| #34376 | ||
| #34776 | ||
| #35283 | ||
| #37701 | ||
| #39186 | ||
| #38736 | ||
| #39884 | ||
| #41484 | ||
| #40999 | ||
| #42621 | ||
| #45012 | ||
| #45722 | ||
| #46257 | ||
| #47962 | ||
| #49083 | ||
| #50503 | ||
| #52549 | ||
| #54405 | ||
| #55175 | ||
| #57438 | ||
| #62234 | ||
| #60788 | ||
| #63144 | ||
| #63825 | ||
| #64311 | ||
| #64730 | ||
| #66224 | ||
| #68039 | ||
| #69269 | ||
| #70744 | ||
| #70895 | ||
| #71786 | ||
| #72154 | ||
| #73092 | ||
| #76233 | ||
| #77115 | ||
| #80923 | ||
| #81163 | ||
| #81518 | ||
| #82108 | ||
| #82402 | ||
| #83274 | ||
| #83647 | ||
| #84288 | ||
| #84818 | ||
| #88259 | ||
| #93069 | ||
| #95887 | ||
| #96571 | ||
| #99005 | ||
| #99054 | ||
| #96043 | ||
| #101262 | ||
| #101359 | ||
| #101200 | ||
| #101872 | ||
| #103999 | ||
| #106453 | ||
| #106597 | ||
| #108122 | ||
| #108980 | ||
| #108915 | ||
| #109130 | ||
| #114713 | ||
| #115088 | ||
| #114213 | ||
| #115479 | ||
| #115975 | ||
| #116439 | ||
| #117007 | ||
| #118393 | ||
| #118425 | ||
| #118817 | ||
| #119811 | ||
| #120109 | ||
| #122505 | ||
| #122536 | ||
| #123694 | ||
| #123652 | ||
| #124925 | ||
| #125239 | ||
| #126221 | ||
| #127547 | ||
| #129873 | ||
| #129997 | ||
| #131565 | ||
| #132055 | ||
| #132147 | ||
| #134559 | ||
| #135544 | ||
| #135675 | ||
| #137260 | ||
| #138054 | ||
| #138926 | ||
| #139146 | ||
| #142828 | ||
| #142620 | ||
| #146242 | ||
| #147282 | ||
| #150427 | ||
| #149798 | ||
| #151629 | ||
| #152164 | ||
| #154276 | ||
| #155426 | ||
| #157667 | ||
| #158258 | ||
| #157951 | ||
| #159775 | ||
| #158870 | ||
| #161372 | ||
| #163062 | ||
| #160990 | ||
| #165325 | ||
| #165865 | ||
| #166558 | ||
| #167280 | ||
| #168013 | ||
| #169850 | ||
| #169077 | ||
| #169991 | ||
| #172594 | ||
| #173234 | ||
| #175091 | ||
| #176046 | ||
| #176505 | ||
| #181374 | ||
| #184630 | ||
| #187198 | ||
| #188717 | ||
| #189085 | ||
| #190792 | ||
| #190848 | ||
| #191329 | ||
| #192120 | ||
| #195552 | ||
| #196453 | ||
| #196659 | ||
| #199550 | ||
| #203215 | ||
| #203715 | ||
| #207157 | ||
| #207660 | ||
| #208349 | ||
| #208987 | ||
| #209582 | ||
| #209409 | ||
| #211078 | ||
| #210511 | ||
| #212657 | ||
| #213437 | ||
| #213927 | ||
| #216853 | ||
| #217342 | ||
| #217887 | ||
| #218974 | ||
| #223295 | ||
| #224981 | ||
| #225165 | ||
| #225043 | ||
| #226920 | ||
| #228150 | ||
| #229583 | ||
| #229995 | ||
| #230738 | ||
| #230547 | ||
| #232776 | ||
| #232976 | ||
| #233681 | ||
| #235876 | ||
| #236322 | ||
| #237100 | ||
| #237662 | ||
| #238691 | ||
| #242069 | ||
| #244032 | ||
| #251812 | ||
| #255219 | ||
| #257287 | ||
| #257702 | ||
| #258518 | ||
| #260785 | ||
| #262201 | ||
| #265244 | ||
| #265410 | ||
| #266383 | ||
| #267555 | ||
| #267072 | ||
| #269978 | ||
| #273157 | ||
| #275654 | ||
| #276490 | ||
| #278203 | ||
| #279273 | ||
| #279498 | ||
| #278032 | ||
| #278233 | ||
| #281111 | ||
| #281097 | ||
| #282528 | ||
| #284576 | ||
| #284799 | ||
| #291249 | ||
| #290586 | ||
| #292672 | ||
| #293232 | ||
| #293607 | ||
| #293163 | ||
| #300368 | ||
| #301051 | ||
| #303190 | ||
| #303498 | ||
| #301638 | ||
| #303848 | ||
| #305687 | ||
| #306357 | ||
| #306253 | ||
| #308014 | ||
| #307177 | ||
| #310527 | ||
| #308575 | ||
| #311978 | ||
| #312720 | ||
| #313495 | ||
| #312861 | ||
| #314350 | ||
| #316405 | ||
| #314395 | ||
| #317714 | ||
| #319163 | ||
| #320590 | ||
| #322793 | ||
| #323488 | ||
| #327938 | ||
| #329615 | ||
| #330244 | ||
| #332609 | ||
| #333344 | ||
| #334031 | ||
| #336170 | ||
| #344046 | ||
| #348457 | ||
| #351454 | ||
| #351672 | ||
| #353870 | ||
| #352236 | ||
| #356899 | ||
| #357659 | ||
| #358134 | ||
| #359895 | ||
| #365481 | ||
| #369067 | ||
| #373243 | ||
| #374894 | ||
| #376058 | ||
| #376492 | ||
| #377246 | ||
| #377909 | ||
| #380623 | ||
| #384256 | ||
| #387751 | ||
| #388771 | ||
| #390363 | ||
| #390774 | ||
| #393880 | ||
| #392682 | ||
| #398058 | ||
| #400322 | ||
| #400917 | ||
| #399582 | ||
| #401880 | ||
| #403456 | ||
| #406242 | ||
| #408518 | ||
| #409274 | ||
| #410784 | ||
| #412398 | ||
| #416301 | ||
| #417659 | ||
| #419886 | ||
| #421845 | ||
| #425290 | ||
| #426168 | ||
| #426281 | ||
| #427018 | ||
| #427972 | ||
| #429269 | ||
| #429686 | ||
| #429675 | ||
| #429927 | ||
| #429996 | ||
| #430509 | ||
| #433023 | ||
| #434404 | ||
| #433723 | ||
| #435143 | ||
| #435903 | ||
| #435517 | ||
| #445305 | ||
| #447478 | ||
| #447672 | ||
| #447839 | ||
| #448714 | ||
| #448326 | ||
| #452379 | ||
| #455719 | ||
| #458475 | ||
| #461166 | ||
| #463835 | ||
| #466116 | ||
| #468744 | ||
| #468998 | ||
| #469650 | ||
| #472967 | ||
| #473548 | ||
| #476742 | ||
| #478536 | ||
| #478801 | ||
| #480996 | ||
| #481406 | ||
| #483657 | ||
| #485014 | ||
| #482313 | ||
| #485271 | ||
| #485684 | ||
| #487486 | ||
| #487231 | ||
| #487601 | ||
| #490385 | ||
| #492412 | ||
| #492959 | ||
| #491489 | ||
| #493494 | ||
| #494464 | ||
| #494182 | ||
| #495559 | ||
| #495983 | ||
| #496743 | ||
| #501558 | ||
| #501215 | ||
| #504971 | ||
| #507800 | ||
| #508028 | ||
| #514574 | ||
| #515795 | ||
| #518244 | ||
| #519159 | ||
| #521881 | ||
| #534625 | ||
| #535860 | ||
| #539272 | ||
| #539595 | ||
| #539634 | ||
| #544041 | ||
| #542311 | ||
| #545723 | ||
| #546337 | ||
| #546779 | ||
| #547976 | ||
| #548412 | ||
| #549677 | ||
| #552481 | ||
| #557293 | ||
| #557812 | ||
| #559553 | ||
| #560800 | ||
| #564265 | ||
| #566382 | ||
| #572103 | ||
| #578631 | ||
| #579627 | ||
| #583760 | ||
| #586907 | ||
| #587361 | ||
| #587407 | ||
| #588300 | ||
| #593281 | ||
| #596082 | ||
| #596227 | ||
| #597568 | ||
| #599060 | ||
| #602675 | ||
| #602896 | ||
| #603252 | ||
| #606778 | ||
| #609724 | ||
| #610255 | ||
| #611309 | ||
| #613479 | ||
| #615877 | ||
| #616237 | ||
| #613931 | ||
| #619524 | ||
| #619859 | ||
| #629656 | ||
| #628139 | ||
| #625891 | ||
| #631390 | ||
| #632156 | ||
| #633751 | ||
| #634264 | ||
| #638620 | ||
| #641207 | ||
| #643922 | ||
| #644243 | ||
| #647183 | ||
| #647310 | ||
| #648258 | ||
| #647136 | ||
| #650575 | ||
| #653316 | ||
| #656782 | ||
| #659092 | ||
| #660536 | ||
| #662385 | ||
| #665239 | ||
| #668554 | ||
| #670181 | ||
| #671372 | ||
| #675029 | ||
| #671549 | ||
| #678461 | ||
| #682325 | ||
| #683822 | ||
| #684119 | ||
| #693825 | ||
| #696084 | ||
| #698854 | ||
| #698891 | ||
| #702301 | ||
| #703138 | ||
| #702924 | ||
| #704880 | ||
| #705409 | ||
| #712067 | ||
| #712723 | ||
| #715017 | ||
| #715989 | ||
| #718055 | ||
| #719564 | ||
| #722720 | ||
| #724539 | ||
| #724273 | ||
| #726293 | ||
| #726321 | ||
| #729120 | ||
| #731835 | ||
| #733620 | ||
| #735147 | ||
| #737519 | ||
| #738078 | ||
| #738430 | ||
| #739286 | ||
| #743174 | ||
| #743649 | ||
| #744387 | ||
| #745990 | ||
| #745531 | ||
| #747150 | ||
| #751212 | ||
| #752139 | ||
| #756665 | ||
| #757106 | ||
| #764895 | ||
| #766379 | ||
| #770888 | ||
| #771599 | ||
| #772193 | ||
| #772273 | ||
| #772633 | ||
| #772840 | ||
| #775495 | ||
| #775550 | ||
| #775851 | ||
| #777621 | ||
| #780599 | ||
| #783820 | ||
| #784471 | ||
| #784836 | ||
| #788042 | ||
| #788545 | ||
| #790642 | ||
| #791326 | ||
| #791748 | ||
| #791329 | ||
| #792314 | ||
| #792717 | ||
| #792939 | ||
| #792821 | ||
| #794659 | ||
| #796406 | ||
| #796583 | ||
| #797744 | ||
| #799173 | ||
| #799069 | ||
| #798559 | ||
| #799679 | ||
| #800629 | ||
| #800630 | ||
| #802157 | ||
| #804079 | ||
| #805563 | ||
| #806583 | ||
| #806242 | ||
| #807293 | ||
| #807528 | ||
| #807530 | ||
| #808087 | ||
| #807992 | ||
| #809306 | ||
| #808751 | ||
| #808755 | ||
| #810275 | ||
| #811277 | ||
| #812104 | ||
| #812651 | ||
| #815464 | ||
| #817318 | ||
| #817531 | ||
| #818989 | ||
| #819328 | ||
| #819463 | ||
| #819577 | ||
| #820871 | ||
| #821949 | ||
| #822862 | ||
| #823287 | ||
| #826451 | ||
| #828876 | ||
| #829590 | ||
| #830433 | ||
| #831897 | ||
| #832324 | ||
| #833058 | ||
| #833094 | ||
| #833133 | ||
| #833057 | ||
| #833885 | ||
| #834423 | ||
| #834417 | ||
| #835273 | ||
| #838771 | ||
| #839150 | ||
| #839041 | ||
| #841042 | ||
| #841576 | ||
| #841610 | ||
| #845763 | ||
| #848471 | ||
| #849274 | ||
| #849068 | ||
| #854611 | ||
| #855881 | ||
| #857784 | ||
| #864946 | ||
| #870365 | ||
| #872862 | ||
| #878513 | ||
| #877817 | ||
| #885902 | ||
| #886884 | ||
| #888332 | ||
| #888426 | ||
| #888673 | ||
| #889056 | ||
| #890734 | ||
| #890777 | ||
| #892113 | ||
| #892544 | ||
| #893079 | ||
| #893914 | ||
| #896040 | ||
| #896964 | ||
| #897006 | ||
| #897925 | ||
| #898715 | ||
| #899000 | ||
| #899547 | ||
| #899715 | ||
| #899918 | ||
| #900226 | ||
| #901102 | ||
| #901329 | ||
| #905894 | ||
| #905780 | ||
| #908428 | ||
| #913850 | ||
| #914418 | ||
| #917795 | ||
| #920340 | ||
| #932190 | ||
| #934605 | ||
| #937837 | ||
| #945158 | ||
| #946903 | ||
| #959243 | ||
| #964258 | ||
| #966768 | ||
| #969450 | ||
| #973830 | ||
| #975958 | ||
| #981134 | ||
| #985412 | ||
| #983139 | ||
| #987346 | ||
| #989387 | ||
| #993208 |
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.