{"id":585,"date":"2010-10-06T12:46:28","date_gmt":"2010-10-06T09:46:28","guid":{"rendered":"http:\/\/dcd.uaic.ro\/?page_id=585"},"modified":"2025-11-13T13:45:38","modified_gmt":"2025-11-13T11:45:38","slug":"dns","status":"publish","type":"page","link":"https:\/\/dcd.uaic.ro\/?page_id=585","title":{"rendered":"DNS"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-page\" data-elementor-id=\"585\" class=\"elementor elementor-585\">\n\t\t\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-796431b elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"796431b\" data-element_type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-100 elementor-top-column elementor-element elementor-element-676212d0\" data-id=\"676212d0\" data-element_type=\"column\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t<div class=\"elementor-element elementor-element-5b8b1bf6 elementor-widget elementor-widget-text-editor\" data-id=\"5b8b1bf6\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p style=\"text-align: center;\"><strong>Domain Name System (Sistemul de Nume de Domenii)<\/strong><\/p><table style=\"border-color: #1c7cf4; height: 147px; text-align: justify;\" border=\"1\" width=\"1137\" cellspacing=\"0\" cellpadding=\"5\"><tbody><tr><td bgcolor=\"#ebebeb\"><strong><span style=\"color: #0000ff;\">Serviciul DNS la D.C.D.I \u015fi RoEduNet<\/span><\/strong><\/td><\/tr><tr><td><div><p>D.C.D.I administreaz\u0103 propriul server DNS cu domain-ul \u00eenregistrat <span style=\"text-decoration: underline;\">uaic.ro<\/span>. Serviciul DNS este disponibil tuturor utilizatorilor Universit\u0103\u0163ii &#8220;Alexandru Ioan Cuza&#8221;, Ia\u015fi: \u00eenregistr\u0103ri de subdomenii (<span style=\"text-decoration: underline;\"><em>nume<\/em>.uaic.ro<\/span>).<\/p><p>\u00cen re\u0163eaua Universit\u0103\u0163ii &#8220;Alexandru Ioan Cuza&#8221;, Ia\u015fi, exist\u0103 un server de nume primar (name server):<\/p><\/div><ul><li><div>Name server <strong>primar:<\/strong> 193.226.23.1 (orion.uaic.ro)<\/div><\/li><\/ul><p>La nivelul <a href=\"http:\/\/www.iasi.roedu.net\/\" target=\"_blank\" rel=\"noopener\">re\u0163elei RoEduNet, Sucursala Ia\u015fi<\/a>, exist\u0103 name serverul 192.129.4.100 (ns.iasi.roedu.net), care poate fi folosit de c\u0103tre to\u0163i cei care se conecteaz\u0103 la re\u0163eaua RoEduNet.<\/p><\/td><\/tr><\/tbody><\/table><table border=\"0\" width=\"100%\" cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td colspan=\"2\"><ul><li><strong><span style=\"color: #0000ff;\">Generalit\u0103\u0163i\/Defini\u0163ii<\/span><\/strong><\/li><\/ul><div><div style=\"text-align: justify;\">DNS este un serviciu de registru Internet distribuit. DNS translateaz\u0103 (&#8220;mapeaz\u0103&#8221;) din nume de domeniu (sau nume ale ma\u015finilor de calcul) \u00een adrese IP \u015fi din adrese IP \u00een nume. Translatarea numelui \u00een adresa IP se nume\u015fte &#8220;rezolvarea numelui de domeniu&#8221;. Cele mai multe servicii Internet se bazeaz\u0103 pe DNS \u015fi dac\u0103 acesta cade, siturile web nu pot fi g\u0103site, iar livrarea mail se blocheaz\u0103.<\/div><p style=\"text-align: justify;\">Numele de domenii sunt mult mai u\u015for de re\u0163inut dec\u00e2t adresele IP, dar nu ofer\u0103 nicio indica\u0163ie despre cum s\u0103 g\u0103si\u0163i situl pe internet. Acest lucru este f\u0103cut de c\u0103tre sistemul DNS, care rezolv\u0103 domeniile \u00een adev\u0103ratele lor adrese &#8211; adresele IP.<\/p><p style=\"text-align: justify;\">O mapare este o simpl\u0103 asociere \u00eentre dou\u0103 lucruri, \u00een acest caz un nume de ma\u015fin\u0103, ca ftp.linux.org, \u015fi IP-ul ma\u015finii (sau adresa) 199.249.150.4.<\/p><p style=\"text-align: justify;\">Un calculator se identific\u0103 printr-o adres\u0103, unic\u0103 \u00een Internet, numit\u0103 adresa IP a calculatorului respectiv. Totodat\u0103, calculatorul poate avea asociat \u015fi un nume. Astfel, adresa IP este utilizat\u0103 la <em>nivelul programelor de prelucrare<\/em>\u00a0\u00een re\u0163ea. La\u00a0<em>nivelul utilizatorilor<\/em>\u00a0cu acces la\u00a0<em>mediul<\/em>\u00a0Internet, identificarea calculatoarelor se face printr-un\u00a0<em><span style=\"text-decoration-line: underline;\">nume de calculator host<\/span><\/em>\u00a0gestionat de sistemul DNS.<\/p><p style=\"text-align: justify;\">Concep\u0163ia protocolului TCP\/IP este implementat\u0103 astfel \u00eenc\u00e2t <em><span style=\"text-decoration-line: underline;\">schema de adresare<\/span><\/em>\u00a0permite utilizatorilor \u015fi programelor din re\u0163ea s\u0103 identifice \u00een mod unic o\u00a0<em>re\u0163ea<\/em>\u00a0sau un\u00a0<em>calculator host<\/em>, at\u00e2t prin intermediul unei\u00a0<em><span style=\"text-decoration-line: underline;\">adrese IP<\/span><\/em>\u00a0(<em><span style=\"text-decoration-line: underline;\">adresa unic\u0103<\/span><\/em>\u00a0pe care o are fiecare calculator cuplat la\u00a0<em>mediul Internet<\/em>), c\u00e2t \u015fi prin intermediul unui\u00a0<em><span style=\"text-decoration-line: underline;\">nume de calculator host<\/span><\/em>. Evident,\u00a0<em>protocolul IP<\/em>\u00a0realizeaz\u0103 o\u00a0<em>coresponden\u0163\u0103 bijectiv\u0103<\/em>\u00a0\u00eentre\u00a0<em>adresele<\/em>\u00a0IP \u015fi\u00a0<em>numele<\/em>\u00a0gestionate de DNS.<\/p><p style=\"text-align: justify;\"><em>Structura<\/em>\u00a0DNS realizeaz\u0103 administrarea unor\u00a0<em><span style=\"text-decoration-line: underline;\">nume<\/span><\/em>\u00a0prin care se acord\u0103 diferite responsabilit\u0103\u0163i de\u00a0<em>grup<\/em>, fiecare nivel reprezent\u00e2nd un\u00a0<em><span style=\"text-decoration-line: underline;\">domeniu<\/span><\/em>.<\/p><\/div><\/td><\/tr><\/tbody><\/table><table border=\"0\" width=\"100%\" cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td colspan=\"2\"><ul><li><strong><span style=\"color: #0000ff;\">Cum func\u0163ioneaz\u0103?<\/span><\/strong><\/li><\/ul><div><p style=\"text-align: justify;\">Fiecare calculator trebuie s\u0103 &#8216;\u015ftie&#8217; de existen\u0163a a cel pu\u0163in un server DNS pentru a rezolva corela\u0163ia \u00eentre un nume calificat de domeniu (FQDN, sau nume de domeniu DNS), adic\u0103 o adres\u0103 literal\u0103 (gen www.google.com, sau\u00a0<strong>www.uaic.ro<\/strong>) \u015fi adresa sa numeric\u0103 (IP address, de tipul\u00a0<strong>193.226.23.4<\/strong>); aceasta pentru c\u0103 o conexiune TCP\/IP \u00eentre 2 calculatoare \u00een Internet se face la nivel de adrese numerice IP.<\/p><p style=\"text-align: justify;\">Dac\u0103 procesul &#8216;resolver&#8217; din calculatorul propriu nu reu\u015fe\u015fte s\u0103 fac\u0103 o c\u0103utare valid\u0103 DNS (acel\u00a0<em>DNS lookup<\/em>), atunci ve\u0163i primi o eroare pentru orice pagin\u0103 web sau server mail, apelate prin numele lor de domeniu.<\/p><p style=\"text-align: justify;\">V\u0103 pute\u0163i convinge c\u0103 exist\u0103 o problem\u0103 DNS &#8211; nu neap\u0103rat la nivel central &#8211; dac\u0103, primind o eroare pentru www.uaic.ro, pute\u0163i totu\u015fi aduce homepage-ul Universit\u0103\u0163ii cu adresa IP echivalent\u0103: 193.226.23.4.<\/p><p style=\"text-align: justify;\"><span style=\"text-decoration: underline;\"><strong>Domeniile \u015fi DNS-ul:<\/strong><\/span><br \/>Sistemul de nume din Internet este structurat pe domenii \u015fi subdomenii. S\u0103 lu\u0103m un server de nume (name server) din Universitatea &#8220;Alexandru Ioan Cuza&#8221;,\u00a0<strong>orion.uaic.ro<\/strong>. Domeniul cel mai larg este &#8220;<strong>ro&#8221;<\/strong>\u00a0care include domeniul &#8220;<strong>uaic&#8221;<\/strong>, iar orion este un computer din cadrul domeniului uaic. Dac\u0103 lu\u0103m de la dreapta la st\u00e2nga un nume, pe prima a pozi\u0163ie se afl\u0103 domeniul general, dup\u0103 care urmeaz\u0103 \u00een ordinea subordon\u0103rii restul subdomeniilor. Pe ultima\u00a0 pozi\u0163ie se afl\u0103 numele computerului.<\/p><p style=\"text-align: justify;\">\u00cen Internet putem avea domenii dedicate (standardizate), c\u00e2teva dintre ele ar fi:\u00a0<em>com<\/em>\u00a0desemneaz\u0103 domeniul comercial,\u00a0<em>edu<\/em>\u00a0desemneaz\u0103 domeniul educa\u0163ional,\u00a0<em>gov<\/em>\u00a0domeniul guvernamental,\u00a0<em>mil\u00a0<\/em>domeniul militar,\u00a0<em>org<\/em>\u00a0alte organiza\u0163ii,\u00a0<em>net<\/em>\u00a0resurse de re\u0163ea,\u00a0<em>int<\/em> resurse interna\u0163ionale etc.<\/p><p style=\"text-align: justify;\">Extinderea Internet-ului \u00een diferite \u0163\u0103ri a dus la crearea de domenii pentru fiecare \u0163ar\u0103:\u00a0<em>ro<\/em>\u00a0&#8211; Rom\u00e2nia,\u00a0<em>fr<\/em>\u00a0&#8211; Fran\u0163a,\u00a0<em>it<\/em>\u00a0&#8211; Italia,\u00a0<em>uk<\/em>\u00a0&#8211; Marea Britanie,\u00a0<em>us\u00a0<\/em>&#8211; USA etc.<\/p><p style=\"text-align: justify;\"><strong><span style=\"text-decoration-line: underline;\">Sistemul de c\u0103utare a unui nume \u00een Internet<\/span><\/strong>:<\/p><p style=\"text-align: justify;\">DNS-ul este o baz\u0103 de date distribuit\u0103 pe toat\u0103 re\u0163eaua Internet, adica nu avem un singur server care s\u0103 con\u021bin\u0103 toat\u0103 informa\u0163ia necesar\u0103 traducerii oric\u0103rui domeniu \u00eentr-o adres\u0103 IP. Fiecare server men\u0163ine o baz\u0103 de date cu propriile domenii pe care sistemele de pe Internet pot s\u0103 o interogheze.<\/p><p style=\"text-align: justify;\">\u00cen Internet exist\u0103 servere (servere DNS) care de\u021bin tabele de coresponden\u0163\u0103 \u00eentre numele cunoscute de fiecare \u015fi adresele fizice corespunz\u0103toare. Fiecare server DNS are un server DNS superior cu ajutorul c\u0103ruia face periodic schimb de informa\u0163ie.\u00a0<em>Sistemul de<\/em>\u00a0<em>name servere autoritare<\/em>\u00a0\u015fi\u00a0<em>servere r\u0103d\u0103cin\u0103<\/em>\u00a0se asigur\u0103 c\u0103 serverele DNS de pretutindeni au acces la aceea\u015fi informa\u0163ie privind adresele IP ale siturilor \u015fi domeniilor web.<\/p><ul style=\"text-align: justify;\"><li style=\"text-align: justify;\"><strong>Servere DNS Autoritare:<\/strong> fiecare domeniu trebuie s\u0103 aib\u0103 2 servere DNS ce func\u0163ioneaz\u0103 ca Autoritar \u015fi Primar. Acestea p\u0103streaz\u0103 cea mai actualizat\u0103 \u015fi corect\u0103 informa\u0163ie privind adresa IP a unui domeniu. De obicei, aceste servere DNS sunt operate de c\u0103tre de\u0163in\u0103torii domeniilor \u00een cauz\u0103. Celelalte servere DNS de pe Internet vor utiliza serverele autoritare, acestea furniz\u00e2ndu-le adresa corect\u0103 pentru un domeniu pe web.<\/li><\/ul><ul style=\"text-align: justify;\"><li style=\"text-align: justify;\"><strong>Servere DNS R\u0103d\u0103cin\u0103:<\/strong> este zona ce con\u021bine cele 13 servere DNS, de\u0163in informa\u0163ia de cel mai \u00eenalt nivel. Aceste 13 sisteme, operate de c\u0103tre mai multe companii private, institu\u0163ii academice \u015fi laboratoare militare, au sarcina de a propaga informa\u0163ia privind adresele IP a fiec\u0103rui server autoritar al unui domeniu, c\u0103tre alte servere DNS de pe Internet.<\/li><\/ul><\/div><\/td><\/tr><\/tbody><\/table><table border=\"0\" width=\"100%\" cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td colspan=\"2\"><ul><li><strong><span style=\"color: #0000ff;\">Exemple <\/span><\/strong><\/li><\/ul><div><div style=\"text-align: justify;\"><p>Recep\u0163ionarea unei adrese IP cu ajutorul unui browser de pe un calculator din interiorul Universit\u0103\u0163ii &#8220;Alexandru Ioan Cuza&#8221;, Ia\u015fi:<\/p><p><strong>Ex: 1)<\/strong>\u00a0\u00cen momentul \u00een care un utilizator se conecteaz\u0103 la &#8216;www.uaic.ro&#8217;, un mesaj este trimis serverului local DNS (orion.uaic.ro) care trimite \u00eenapoi adresa IP a domeniului: 193.226.23.4. Browserul folose\u015fte acest IP pentru a se conecta la serverul web \u015fi pentru a primi paginile.<\/p><p><strong>Ex: 2)<\/strong>\u00a0Dac\u0103 utilizatorul dore\u015fte s\u0103 acceseze\u00a0<a href=\"http:\/\/www.microsoft.ro\/\">www.microsoft.ro<\/a><\/p><\/div><div style=\"text-align: justify;\"><ol><li style=\"text-align: justify;\">Utilizatorul introduce &#8216;www.microsoft.com&#8217; \u00een bara de adrese a browserului<ul><li style=\"text-align: justify;\">Browserul trimite un mesaj serverului DNS al Furnizorului de Servicii Internet (D.C.D.).<\/li><\/ul><\/li><li style=\"text-align: justify;\">Serverul se uit\u0103 \u00een \u00eenregistr\u0103rile sale pentru a vedea dac\u0103 are adresa sitului\u00a0<a href=\"http:\/\/www.microsoft.com\/\">www.microsoft.com<\/a><ul><li style=\"text-align: justify;\">V\u0103z\u00e2nd c\u0103 nu are adresa sitului www.microsoft.com, trebuie s\u0103 o solicite unui server r\u0103d\u0103cin\u0103.<\/li><\/ul><\/li><li style=\"text-align: left;\">microsoft.com face parte din .com TLD [top-level-domain], a\u015fa c\u0103 \u00eentreab\u0103 un server r\u0103d\u0103cin\u0103 responsabil cu .com TLD [serverul r\u0103d\u0103cin\u0103 are o list\u0103 cu toate domeniile .com cunoscute, precum \u015fi cu serverele autoritare ale fiec\u0103rui domeniu]<br \/><ul style=\"text-align: justify;\"><li style=\"text-align: justify;\">Serverul r\u0103d\u0103cin\u0103 se conecteaz\u0103 la adresa IP 131.107.1.240, serverul autoritar pentru microsoft.com, de unde prime\u015fte adresa IP pentru\u00a0<a href=\"http:\/\/www.microsoft.com\/\">www.microsoft.com<\/a><\/li><\/ul><\/li><li style=\"text-align: justify;\">Serverul r\u0103d\u0103cin\u0103 d\u0103 \u00eenapoi serverului DNS al Furnizorului de Servicii Internet (D.C.D.) aceast\u0103 adres\u0103, care la r\u00e2ndul lui o va pasa \u00eenapoi browserului utilizatorului. Browserul se conecteaz\u0103 la adresa IP \u015fi prime\u015fte paginile de la\u00a0<a href=\"http:\/\/www.microsoft.com\/\">www.microsoft.com<\/a>.<\/li><li style=\"text-align: justify;\">Serverul DNS al ISP-ului utilizatorului p\u0103streaz\u0103 adresa www.microsoft.com \u00een cache-ul DNS propriu. Data viitoare c\u00e2nd cineva conectat la acela\u015fi ISP dore\u015fte s\u0103 se conecteze la microsoft.com, va avea adresa stocat\u0103 local \u015fi o poate rezolva mult mai rapid.<\/li><li style=\"text-align: justify;\">\u00cen func\u0163ie de cum a configurat Furnizorul de Servicii Internet (D.C.D.) serverele DNS proprii, adresa poate fi p\u0103strat\u0103 \u00een cache pentru c\u00e2teva ore sau c\u00e2teva zile. Acest lucru este important de \u015ftiut, deoarece, dac\u0103 adresa IP a microsoft.com [sau a oric\u0103rui domeniu] se schimb\u0103 \u00een intervalul respectiv, serverul DNS nu o va mai solicita serverelor r\u0103d\u0103cin\u0103 p\u00e2n\u0103 c\u00e2nd nu expir\u0103 cache-ul.<\/li><\/ol><\/div><\/div><\/td><\/tr><\/tbody><\/table><table border=\"0\" width=\"100%\" cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td colspan=\"2\"><ul><li><strong><span style=\"color: #0000ff;\">Beneficiile DNS-ului<\/span><\/strong><\/li><\/ul><div><ul><li style=\"text-align: justify;\">numele de domenii sunt mult mai u\u015for de re\u0163inut dec\u00e2t adresele IP;<\/li><li style=\"text-align: justify;\">putem schimba unde se \u00eendreapt\u0103 un domeniu prin schimbarea adresei IP c\u0103tre care redirec\u0163ioneaz\u0103 serverul DNS &#8211; un site se poate muta pe un alt computer, \u00een cealalt\u0103 parte a lumii, \u015fi totu\u015fi va r\u0103m\u00e2ne accesibil prin domeniul s\u0103u web, at\u00e2ta timp c\u00e2t sistemul DNS este adus la zi cu noua adres\u0103 IP;<\/li><li style=\"text-align: justify;\">identific\u0103 \u00een mod unic o\u00a0<em>re\u0163ea<\/em>\u00a0sau un\u00a0<em>calculator host<\/em>, at\u00e2t prin intermediul unei\u00a0<em><span style=\"text-decoration-line: underline;\">adrese IP<\/span><\/em>, c\u00e2t \u015fi prin intermediul unui\u00a0<em><span style=\"text-decoration-line: underline;\">nume de calculator host<\/span><\/em>.<\/li><\/ul><\/div><\/td><\/tr><\/tbody><\/table><table border=\"0\" width=\"100%\" cellspacing=\"0\" cellpadding=\"0\"><tbody><tr><td colspan=\"2\"><ul><li><strong><span style=\"color: #0000ff;\">Leg\u0103turi:<\/span><\/strong><\/li><\/ul><div><ul><li><a href=\"http:\/\/www.ibiblio.org\/pub\/Linux\/docs\/HOWTO\/translations\/ro\/text\/DNS-HOWTO\" target=\"_blank\" rel=\"noopener\">http:\/\/www.ibiblio.org\/pub\/Linux\/docs\/HOWTO\/translations\/ro\/text\/DNS-HOWTO<\/a><\/li><li><a href=\"http:\/\/en.wikipedia.org\/wiki\/Domain_Name_System\" target=\"_blank\" rel=\"noopener\">http:\/\/en.wikipedia.org\/wiki\/Domain_Name_System<\/a><\/li><\/ul><\/div><\/td><\/tr><\/tbody><\/table>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t<\/div>\n\t\t<div class=\"gsp_post_data\" data-post_type=\"page\" data-cat=\"\" data-modified=\"120\" data-title=\"DNS\" data-home=\"https:\/\/dcd.uaic.ro\"><\/div>","protected":false},"excerpt":{"rendered":"<p>Domain Name System (Sistemul de Nume de Domenii) Serviciul DNS la D.C.D.I \u015fi RoEduNet D.C.D.I administreaz\u0103 propriul server DNS cu domain-ul \u00eenregistrat uaic.ro. Serviciul DNS este disponibil tuturor utilizatorilor Universit\u0103\u0163ii &#8220;Alexandru Ioan Cuza&#8221;, Ia\u015fi: \u00eenregistr\u0103ri de subdomenii (nume.uaic.ro). \u00cen re\u0163eaua Universit\u0103\u0163ii &#8220;Alexandru Ioan Cuza&#8221;, Ia\u015fi, exist\u0103 un server de nume primar (name server): Name server [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":113,"menu_order":2,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-585","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/dcd.uaic.ro\/index.php?rest_route=\/wp\/v2\/pages\/585","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dcd.uaic.ro\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/dcd.uaic.ro\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/dcd.uaic.ro\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dcd.uaic.ro\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=585"}],"version-history":[{"count":6,"href":"https:\/\/dcd.uaic.ro\/index.php?rest_route=\/wp\/v2\/pages\/585\/revisions"}],"predecessor-version":[{"id":6358,"href":"https:\/\/dcd.uaic.ro\/index.php?rest_route=\/wp\/v2\/pages\/585\/revisions\/6358"}],"up":[{"embeddable":true,"href":"https:\/\/dcd.uaic.ro\/index.php?rest_route=\/wp\/v2\/pages\/113"}],"wp:attachment":[{"href":"https:\/\/dcd.uaic.ro\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=585"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}