Is file /etc/hostname ever used for host name resolution?












1















When setting up a local Wi-Fi network in a small place from an ISP, such as Verizon, using a router and modem, the machines in the network are assigned private IP addresses.



In such a local Wi-Fi network, I can use ssh name@<hostname> to access an SSH server on another computer <hostname>, where <hostname> is the output of command hostname. Is the output of hostname resolved to a private IP address, by some DNS server (possibly on the router?)?



But I heard that the output of hostname is unrelated to host name resolution by DNS. Then why can I successfully run ssh name@<hostname>, where <hostname> is the output of command hostname?






linux domain-name-system hostname







share|improve this question





























    1















    When setting up a local Wi-Fi network in a small place from an ISP, such as Verizon, using a router and modem, the machines in the network are assigned private IP addresses.



    In such a local Wi-Fi network, I can use ssh name@<hostname> to access an SSH server on another computer <hostname>, where <hostname> is the output of command hostname. Is the output of hostname resolved to a private IP address, by some DNS server (possibly on the router?)?



    But I heard that the output of hostname is unrelated to host name resolution by DNS. Then why can I successfully run ssh name@<hostname>, where <hostname> is the output of command hostname?






    linux domain-name-system hostname







    share|improve this question



























      1












      1








      1








      When setting up a local Wi-Fi network in a small place from an ISP, such as Verizon, using a router and modem, the machines in the network are assigned private IP addresses.



      In such a local Wi-Fi network, I can use ssh name@<hostname> to access an SSH server on another computer <hostname>, where <hostname> is the output of command hostname. Is the output of hostname resolved to a private IP address, by some DNS server (possibly on the router?)?



      But I heard that the output of hostname is unrelated to host name resolution by DNS. Then why can I successfully run ssh name@<hostname>, where <hostname> is the output of command hostname?






      linux domain-name-system hostname







      share|improve this question
















      When setting up a local Wi-Fi network in a small place from an ISP, such as Verizon, using a router and modem, the machines in the network are assigned private IP addresses.



      In such a local Wi-Fi network, I can use ssh name@<hostname> to access an SSH server on another computer <hostname>, where <hostname> is the output of command hostname. Is the output of hostname resolved to a private IP address, by some DNS server (possibly on the router?)?



      But I heard that the output of hostname is unrelated to host name resolution by DNS. Then why can I successfully run ssh name@<hostname>, where <hostname> is the output of command hostname?






      linux domain-name-system hostname




      linux domain-name-system hostname






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited 26 mins ago









      Peter Mortensen

      2,13242124




      2,13242124










      asked 7 hours ago









      TimTim

      69231526




      69231526






















          2 Answers
          2






          active

          oldest

          votes


















          4














          Linux systems using nss-myhostname will resolve the currently configured local hostname (which on some systems comes from /etc/hostname), when you use getaddrinfo/gethostbyname. Systems without nss-myhostname usually have the local hostname listed in /etc/hosts, and resolve the local hostname that way.



          If you specifically do dns lookups (e.g. with nslookup or dig), that bypasses nss and only uses dns, so nss-myhostname doesn't get a chance to influence the result.



          If you want ssh@<hostname> to work from other devices, make sure hostname resolves in dns, or is listed in /etc/hosts on those devices.






          share|improve this answer
























          • Thanks. Updated my post to avoid misleading.

            – Tim
            6 hours ago



















          1














          There are a couple of mechanisms that could be at work here.



          Firstly, a system will often include its locally-configured hostname as a DHCP Client Identifier, and the router (which is also the DHCP and DNS server) will dynamically add a DNS record for that client ID matching the IP it gave out for that request.



          The other likely case is that the system is advertizing it's locally-configured hostname using Multicast DNS Service Discovery (via Bonjour services on macOS, or the avahi daemon on Linux), and many modern distros include mDNS in their NSS lookup chain by default.






          share|improve this answer























            Your Answer








            StackExchange.ready(function() {
            var channelOptions = {
            tags: "".split(" "),
            id: "2"
            };
            initTagRenderer("".split(" "), "".split(" "), channelOptions);

            StackExchange.using("externalEditor", function() {
            // Have to fire editor after snippets, if snippets enabled
            if (StackExchange.settings.snippets.snippetsEnabled) {
            StackExchange.using("snippets", function() {
            createEditor();
            });
            }
            else {
            createEditor();
            }
            });

            function createEditor() {
            StackExchange.prepareEditor({
            heartbeatType: 'answer',
            autoActivateHeartbeat: false,
            convertImagesToLinks: true,
            noModals: true,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: 10,
            bindNavPrevention: true,
            postfix: "",
            imageUploader: {
            brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
            contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
            allowUrls: true
            },
            onDemand: true,
            discardSelector: ".discard-answer"
            ,immediatelyShowMarkdownHelp:true
            });


            }
            });














            draft saved

            draft discarded


















            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fserverfault.com%2fquestions%2f953448%2fis-file-etc-hostname-ever-used-for-host-name-resolution%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown

























            2 Answers
            2






            active

            oldest

            votes








            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            4














            Linux systems using nss-myhostname will resolve the currently configured local hostname (which on some systems comes from /etc/hostname), when you use getaddrinfo/gethostbyname. Systems without nss-myhostname usually have the local hostname listed in /etc/hosts, and resolve the local hostname that way.



            If you specifically do dns lookups (e.g. with nslookup or dig), that bypasses nss and only uses dns, so nss-myhostname doesn't get a chance to influence the result.



            If you want ssh@<hostname> to work from other devices, make sure hostname resolves in dns, or is listed in /etc/hosts on those devices.






            share|improve this answer
























            • Thanks. Updated my post to avoid misleading.

              – Tim
              6 hours ago
















            4














            Linux systems using nss-myhostname will resolve the currently configured local hostname (which on some systems comes from /etc/hostname), when you use getaddrinfo/gethostbyname. Systems without nss-myhostname usually have the local hostname listed in /etc/hosts, and resolve the local hostname that way.



            If you specifically do dns lookups (e.g. with nslookup or dig), that bypasses nss and only uses dns, so nss-myhostname doesn't get a chance to influence the result.



            If you want ssh@<hostname> to work from other devices, make sure hostname resolves in dns, or is listed in /etc/hosts on those devices.






            share|improve this answer
























            • Thanks. Updated my post to avoid misleading.

              – Tim
              6 hours ago














            4












            4








            4







            Linux systems using nss-myhostname will resolve the currently configured local hostname (which on some systems comes from /etc/hostname), when you use getaddrinfo/gethostbyname. Systems without nss-myhostname usually have the local hostname listed in /etc/hosts, and resolve the local hostname that way.



            If you specifically do dns lookups (e.g. with nslookup or dig), that bypasses nss and only uses dns, so nss-myhostname doesn't get a chance to influence the result.



            If you want ssh@<hostname> to work from other devices, make sure hostname resolves in dns, or is listed in /etc/hosts on those devices.






            share|improve this answer













            Linux systems using nss-myhostname will resolve the currently configured local hostname (which on some systems comes from /etc/hostname), when you use getaddrinfo/gethostbyname. Systems without nss-myhostname usually have the local hostname listed in /etc/hosts, and resolve the local hostname that way.



            If you specifically do dns lookups (e.g. with nslookup or dig), that bypasses nss and only uses dns, so nss-myhostname doesn't get a chance to influence the result.



            If you want ssh@<hostname> to work from other devices, make sure hostname resolves in dns, or is listed in /etc/hosts on those devices.







            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered 6 hours ago









            Dennis KaarsemakerDennis Kaarsemaker

            15.8k3766




            15.8k3766













            • Thanks. Updated my post to avoid misleading.

              – Tim
              6 hours ago



















            • Thanks. Updated my post to avoid misleading.

              – Tim
              6 hours ago

















            Thanks. Updated my post to avoid misleading.

            – Tim
            6 hours ago





            Thanks. Updated my post to avoid misleading.

            – Tim
            6 hours ago













            1














            There are a couple of mechanisms that could be at work here.



            Firstly, a system will often include its locally-configured hostname as a DHCP Client Identifier, and the router (which is also the DHCP and DNS server) will dynamically add a DNS record for that client ID matching the IP it gave out for that request.



            The other likely case is that the system is advertizing it's locally-configured hostname using Multicast DNS Service Discovery (via Bonjour services on macOS, or the avahi daemon on Linux), and many modern distros include mDNS in their NSS lookup chain by default.






            share|improve this answer




























              1














              There are a couple of mechanisms that could be at work here.



              Firstly, a system will often include its locally-configured hostname as a DHCP Client Identifier, and the router (which is also the DHCP and DNS server) will dynamically add a DNS record for that client ID matching the IP it gave out for that request.



              The other likely case is that the system is advertizing it's locally-configured hostname using Multicast DNS Service Discovery (via Bonjour services on macOS, or the avahi daemon on Linux), and many modern distros include mDNS in their NSS lookup chain by default.






              share|improve this answer


























                1












                1








                1







                There are a couple of mechanisms that could be at work here.



                Firstly, a system will often include its locally-configured hostname as a DHCP Client Identifier, and the router (which is also the DHCP and DNS server) will dynamically add a DNS record for that client ID matching the IP it gave out for that request.



                The other likely case is that the system is advertizing it's locally-configured hostname using Multicast DNS Service Discovery (via Bonjour services on macOS, or the avahi daemon on Linux), and many modern distros include mDNS in their NSS lookup chain by default.






                share|improve this answer













                There are a couple of mechanisms that could be at work here.



                Firstly, a system will often include its locally-configured hostname as a DHCP Client Identifier, and the router (which is also the DHCP and DNS server) will dynamically add a DNS record for that client ID matching the IP it gave out for that request.



                The other likely case is that the system is advertizing it's locally-configured hostname using Multicast DNS Service Discovery (via Bonjour services on macOS, or the avahi daemon on Linux), and many modern distros include mDNS in their NSS lookup chain by default.







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 5 hours ago









                techieb0ytechieb0y

                3,8511315




                3,8511315






























                    draft saved

                    draft discarded




















































                    Thanks for contributing an answer to Server Fault!


                    • Please be sure to answer the question. Provide details and share your research!

                    But avoid …



                    • Asking for help, clarification, or responding to other answers.

                    • Making statements based on opinion; back them up with references or personal experience.


                    To learn more, see our tips on writing great answers.




                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function () {
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fserverfault.com%2fquestions%2f953448%2fis-file-etc-hostname-ever-used-for-host-name-resolution%23new-answer', 'question_page');
                    }
                    );

                    Post as a guest















                    Required, but never shown





















































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown

































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown







                    -

                    Popular posts from this blog

                    サソリ

                    Image
                    この記事は検証可能な参考文献や出典が全く示されていないか、不十分です。 出典を追加して記事の信頼性向上にご協力ください。 （ 2019年1月 ） 「 サソリ 」のその他の用法については「サソリ (曖昧さ回避)」をご覧ください。 「 スコーピオン 」と「 スコルピオン 」はこの項目へ転送されています。その他の用法については「スコーピオン」をご覧ください。 サソリ目 生息年代: 430–0 Ma PreЄ Є O S D C P T J K Pg N シルル紀前期-現世 ダイオウサソリ（ Pandinus Imperator ） 分類 界 : 動物界 Animalia 門 : 節足動物門 Arthropoda 亜門 : 鋏角亜門 Chelicerata 綱 : クモガタ綱 Arachnida 目 : サソリ目 Scorpiones 学名 Scorpiones C. L. Koch, 1837 英名 Scorpion 上科 Pseudochactoidea キョクトウサソリ上科 Buthoidea Chaeriloidea Chactoidea Iuroidea Scorpionoidea サソリ （ サソリ類 、 蠍 、 蝎 、 scorpion ）は、鋏角亜門・クモガタ綱の サソリ目 （ Scorpiones ）に属する節足動物の総称である。体の前端に鋏型の触肢、後端に毒針を有する捕食者である。 1700種以上を含め、最古の化石記録は4億3千万年前のシルル紀まで遡る。有毒生物として広く知られるが、人間の命にかかわる毒を持つものはごく一部の種類に過ぎない。 目次 1 形態 1.1 前体 1.2 後体 1.2.1 中体 1.2.2 終体 2 雌雄 3 生態 3.1 天敵 3.2 生殖 4 分布 5 毒 6 蛍光現象 7 分類
                    Read more

                    広島県道265号伴広島線

                    Image
                    一般県道 広島県道265号伴広島線 路線延長 km 起点 広島県広島市安佐南区伴東7丁目 終点 広島県広島市中区榎町 接続する 主な道路 （記法） 広島県道38号広島豊平線 広島県道71号広島湯来線 山陽自動車道五日市IC 国道183号（ 国道261号重複） ■テンプレート（■ノート ■使い方） ■PJ道路 広島県道265号伴広島線 （ひろしまけんどう265ごう ともひろしません）は広島県広島市安佐南区から広島県広島市中区を結ぶ一般県道である。 目次 1 路線データ 2 通過する自治体 3 見どころ 4 接続道路 4.1 本線 4.2 旧道 5 別名 6 関連項目 路線データ 本線 起点：広島市安佐南区伴東7丁目・大原下橋南詰交差点（広島県道38号広島豊平線（本線・旧道）交点） 終点：広島市中区榎町・十日市交差点（国道183号（国道261号重用）交点） 総延長： 旧道 起点：広島市安佐南区伴東4丁目・新細坂交差点（広島県道38号広島豊平線交点） 終点：広島市安佐南区伴中央4丁目・寺組橋(南)交差点（広島県道265号伴広島線（本線）交点） 総延長： 通過する自治体 広島県 広島市（安佐南区、佐伯区、西区、中区） 見どころ 広島高速交通広島新交通1号線（アストラムライン） 広島広域公園 広島広域公園陸上競技場（広島ビッグアーチ） 己斐峠 己斐橋（太田川放水路） 天満橋（天満川） 接続道路 本線 広島県道38号広島豊平線（本線・旧道）（広島市安佐南区伴東7丁目・大原下橋南詰交差点〔起点〕） 広島県道71号広島湯来線（本線）（広島市安佐南区伴中央2丁目・伴交番入口交差点 - 広島市安佐南区伴中央4丁目・寺組橋(南)交差点間で重用） 広島県道71号広島湯来線（旧道）（広島県道265号伴広島線（旧道）重用）（広島市安佐南区伴中央4丁目・寺組橋(南)交差点） 広島県道71号広島湯来線（広島市安佐南区伴中央4丁目・寺組橋(南)交差点 - 広島市佐伯区五日市町石内・五月が丘(南)交差点間で重用）
                    Read more

                    Setup Asymptote in Texstudio

                    Image
                    0 Good time of the day! I am trying to compile the following file: documentclass[12pt]{article} usepackage[inline]{asymptote} begin{document} Here is a venn diagram produced with Asymptote, drawn to width 4cm: defA{A} defB{V{B}} begin{figure} begin{center} begin{asy} size(4cm,0); pen colour1=red; pen colour2=green; pair z0=(0,0); pair z1=(-1,0); pair z2=(1,0); real r=1.5; path c1=circle(z1,r); path c2=circle(z2,r); fill(c1,colour1); fill(c2,colour2); picture intersection=new picture; fill(intersection,c1,colour1+colour2); clip(intersection,c2); add(intersection); draw(c1); draw(c2); //draw("$A$",box,z1)
                    Read more