Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1431 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1431 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1431 Deprecated: str_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1431 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442 Warning: Undefined variable $blocks in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Warning: Trying to access array offset on value of type null in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1441 Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /customers/c/9/8/wpin4.1prod.one/httpd.www/landing-v2/wp-content/themes/onecom-landing-page-v2/functions.php on line 1442

Hvad står DNS for?

Læs her om DNS -serverprocessen, der giver dig mulighed for at besøge alle dine yndlingshjemmesider

DNS står for Domain Name System og ved at gøre brug af en navneserver, som den også bliver kaldt, har din computer eller mobiltelefon meget lettere ved at få adgang til de sider, som du ønsker at besøge.

DNS, navnserveren fungerer ligesom en taxi, hvis man skal bruge en metafor. Når du sætter dig ind i en taxi, så skal du kunne fortælle chaufføren adressen for at komme til den rigtige destination. Det samme gør sig gældende for DNS. DNS oversætter URL’en for en bestemt hjemmeside til en talkode (IP-adresse), fordi computere kun forstår disse talkoder. Så når du skriver en URL, så oversætter navnserveren den til en IP-adresse.

Når du skriver en hjemmesides adresse, f.eks. www.one.com, har din computer brug for en IP-adresse for at finde vej til one.com’s website. For at din computer skal få adgang til IP-adressen, der matcher one.com, sendes der en anmodning til DNS. Når anmodningen er modtaget, så matches en IP-adresse med den URL, som du har indtastet i din browser, og du får nu adgang til hjemmesiden.

Dybest set er en navneserver ligesom en telefonbog, der blot fungerer i relation til internettet. Når du leder efter et nummer i telefonbogen, så leder du ikke automatisk efter nummeret. Du kigger derimod efter navnet på den person, som du ønsker at ringe til.

Hvordan virker DNS?

En DNS-forespørgsel sætter gang i kædereaktion af forskellige processer. Hvis din computer kan finde IP-adressen, der er gemt i cachehukommelsen, er det ikke nødvendigt at gennemgå alle led i processen. Har du med andre ord besøgt en hjemmeside før, så vil IP-adressen ligge som en cachede (gemt) version på din computer, hvis du da ikke har valgt at slette alle cachede versioner fra hukommelsen.

Men hvis det er første gang du besøger et websted, så fungerer DNS ved at domænenavnet, der er indtastet i browseren, omformes til en IP-adresse, således at computeren kan finde vej til den pågældende hjemmeside. Så DNS er altså en form for oversættelsestjeneste, og først når taladressen er modtaget kan hjemmesiden indlæses i din browser.

DNS resolver

Anmodninger til navnserveren skal først gå til en rekursiv navneserver, også kendt som en DNS-resolver, en server, som din internetudbyder driver. Den rekursive navneserver har muligvis allerede gemt den IP-adresse, der anmodes om, så den kontrollerer først, om den kan finde den i arkivet. Hvis den rekursive navneserver ikke har IP-adressen gemt, går forespørgslen automatisk videre til en af mange DNS-rodservere.

Tænk på denne DNS-resolver som en bibliotekar, der prøver at finde en bog til dig på biblioteket.

Det er den rekursive navneserver, der tager sig tid til at svare på din anmodning, når den har modtaget din henvendelse via DNS-serveren. For at finde den rigtige bog sender DNS-resolveren forespørgsler afsted til sit netværk, som har mere konkret viden om bogens placering, og som vil se om de kan finde den i arkivet.

Rodnavneservere

De utallige rodnavneservere administrerer topdomæner (TLD) såsom .com. Der er tretten sæt af disse rodservere, som tolv forskellige organisationer driver. Disse servere står spredt ud over det meste af kloden for at sikre, at alle indgående anmodninger håndteres hurtigst muligt.

Når en DNS-resolver sender en anmodning til rodnavneserveren, kan denne ikke svare på anmodningen om den ønskede IP-adresse. I stedet omdirigerer rodnavneserveren anmodningen fra DNS-resolveren til TLD-navneserveren.

Topdomæne-navneserver

Med rodnavneserverens hjælp beder DNS-resolveren nu topdomæneserveren om IP-adressen. I dette tilfælde ville det være .com, når du prøver at tjekke vores hjemmeside www.one.com for at læse denne artikel.

Topdomæneserveren gemmer alle adresseoplysninger til topdomæner. Når DNS-resolveren sender en anmodning om IP-adressen til one.com, så kender TLD-navneserveren heller ikke IP-adressen. Endnu en gang vil TLD-navneserveren omdirigere DNS-resolveren til den respektive navneserver som det sidste led i processen.

Autoritativ navneserver

DNS-resolveren vil nu anmode om IP-adressen på one.com. Det sker gennem den autoritative navneserver, der indeholder en autoritativ liste over IP-adresser og matchende URL’er. De autoritative navneservere er ansvarlige for at holde styr på alle domæner. Denne autoritative liste opdateres derfor hver gang nogen køber og registrerer et nyt domæne.

Den autoritative navneserver er det sidste stop i DNS-opslagsprocessen. Det er i sidste ende den autoritative navneserver, der tillader at du ved hjælp af IP-adressen får adgang til den hjemmeside, som du har forespurgt på.

Når den autoritative navneserver modtager anmodningen, svarer den med IP-adressen til one.com. Dette gør det muligt for DNS-revolveren at videreformidle IP-adressen, og din computer kan nu hente one.com.

For at denne proces kan gå hurtigere, næste gang du vil besøge en hjemmeside, så vil din computer og den rekursive navneserver gemme den seneste version som en cachet fil. På den måde kender din computer den korrekte IP-adresse næste gang, eller den kan hente den fra den rekursive server uden at skulle igennem alle de andre forskellige anmodninger.

Hvad er min DNS-server?

Det er din netværksudbyder, der automatisk aktiverer din DNS-server, når du prøver at oprette forbindelse til internettet. Nogle hjemmesider kan hjælpe dig med at få oplysninger om din netværksforbindelse. Browserleaks er et godt website, der gør dig i stand til at finde din DNS-server.

Det skal du være opmærksom på

Som med alt andet på internettet, så skal du sikre dig, at du er beskyttet mod hackere og virusangreb. Nedenfor giver vi dig et par eksempler på nogle DNS-angreb, der desværre kan forekomme, og som du skal være opmærksom på:

  • DNS-refleksionsangreb

DNS-refleksionsangreb betyder at ofre for disse angreb modtager mange henvendelser og at hjemmesiden derfor bliver ’oversvømmet’ med trafik. Hackerne forsøger at finde store DNS-filer fra DNS-resolverservere, der er åbne; de gør dette ved hjælp af ofrenes IP-adresse. Derfor, når DNS-resolveren svarer på anmodningen, vil offeret modtage flere DNS-data, der giver så stor en belastning på hjemmesiden at den risikerer at gå ned.

  • DNS cache forgiftning

DNS-cache-forgiftning, eller spoofing, kan lokke brugere hen til hjemmesider med ondsindede hensigter. Personerne bag den slags cyberangreb gør dette ved at forfalske adresseoptegnelser i DNS. Når en person således anmoder om IP-adressen for et af disse websites, der er blevet forgiftet, vil DNS svare med en IP-adresse fra et forfalsket website, som angriberen kontrollerer. Brugeren bliver nu omdirigeret til den falske server, hvor de cyberkriminelle vil forsøge at franarre personerne deres adgangskoder eller andre personlige oplysninger.

  • DNS-ressourceudmattelse

Et angreb der sker som en DNS-ressourceudmattelse (lammelsesangreb) har til hensigt at blokere internetudbyderens infrastruktur, så brugere ikke kan besøge hjemmesider, der er hostet hos udbyderen. Hackerne gør dette ved både at bruge offerets navneserver samt domænets autoritative server. Dette vil resultere i en overvældende mængde anmodninger, som altså vil få serveren til at gå ned.

DNS-sikkerhedsudvidelse

Internet Corporation for Assigned Names and Numbers, også kendt som ICANN, har udviklet en DNS sikkerhedsudvidelse for at sikre, at kommunikationen mellem de forskellige niveauer af DNS-servere bliver mere sikker.

DNSSec blev udviklet for at sikre, at hackerne ikke kan bryde DNS-opslag, der ellers kan føre til ubehagelige og ødelæggende phishing-angreb. Processen med DNSSec er, at for hvert niveau af DNS-opslag skal du underskrive og bekræfte, at der ikke står hackere bag anmodningen.