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Questions tagged [domain-name-system]

The Domain Name System, usually referred to by the acronym DNS, is a hierarchical, distributed database where the keys are domain names. Questions involving publicly accessible domains should include the real, Fully Qualified Domain Name (FQDN)

DNS is the Domain Name System, a hierarchical, distributed database where the keys are domain names.

The primary references are:

  • RFC 1034 - Domain Names - Concepts and Facilities
  • RFC 1035 - Domain Names - Implementation and Specification

These documents collectively form STD 13. RFC 2181 is a frequently cited reference for STD 13 that addresses some of the more confusing areas of operation.

The most common record types found in the DNS are:

  • "A" records - the mapping from a domain name to an IPv4 address
  • "AAAA" records - the mapping from a domain name to an IPv6 address
  • "MX" records - the mapping from a domain name to the host name of an SMTP server
  • "NS" records - used to delegate a portion of the hierarchy to specific DNS servers
  • "PTR" records - typically used (via in-addr.arpa.) to map an IPv4 address back to a domain name
  • "CNAME" records - used to alias a domain name to its canonical version

DNS packets are conventionally transported over UDP and TCP port 53. UDP is more commonly used, but larger DNS responses and zone transfers require TCP. See RFC 5966.

This Wikipedia article provides an approachable introduction to DNS.

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DCDIAG CrossRefValidation test fails because of the dnsRoot value of ForestDnsZones

A while ago I promoted our DNS server (running 2003) from being a member server to a domain controller so I could enable AD integrated DNS. Often, I am seeing error 9906 (Event ID 4512) pop up in the logs. The body of the message error is: The DNS…
Bourne
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DNS requests failing from computers that can ping DNS server

I have a situation where computers in some of our remote offices from time to time lose the ability to use our DNS server (in head office) to resolve hostnames. The offices are connected via VPN using Cisco ASA 5505 (VPNclient config rather than…
dunxd
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DNS query appending parent suffix twice

We're having an issue with DNS clients not being able to resolve certain FQDNs. Within the same domain in which the problem occurs, doing an nslookup against a host name works. However, an nslookup against the…
sjw
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Dns server which is better bind or mydns?

I am going to start a new website which is going to require DNS servers. It might have over 10,000 zones and will get more zone files as we get bigger. The problem is, which dns server software do you think is more efficent: mydns which uses mysql…
Nesh A
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Multiple DNS servers in multiple countries, which one will respond to DNS lookup request?

If I have 1 DNS server in the US, and 1 in the EU... if I'm in the EU and type in "www.mydomain.com" and it resolves, which server would handle the query? EU or US? Consider that my US DNS Server is "ns1" and the other "ns2" and it's been setup, in…
AcidRaZor
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Why are domain names occasionally inaccessible?

I could not track down the reason why my domain names occasionally are inaccessible to some visitors. With some I mean some, not everyone. I was working on my website, and at some moment I could not access it anymore. I thought that it's a…
afaf12
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How to prevent dns recursive queries on a Windows 2008 R2 server?

I have been tasked in managing a server, but I did not receive any training concerning DNS configuration. I come from the programming world, so I'm aware of certain concept, but not everything. We are having trouble with some ISP when we try to send…
Pierre-Alain Vigeant
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How to create a catch-all subdomain in IIS 7.5?

How can I create a catchall for any unspecified subdomains of website.com in IIS 7.5 on Windows Server 2008 RC2? I have already configured a CNAME DNS entry for *.website.com pointing to website.com. The behavior I am trying to achieve is that…
smartcaveman
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GitHub Pages and DNS Records

I want to have my new site located at GitHub Pages, but unfortunately I've been using an email account with the domain I want to point to GitHub. So, I have this paid hosting where I'm receiving my emails, my domain name registered at GoDaddy, and I…
Andrés
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How does an automatic secondary DNS server figure out the correct records?

For our servers hosted at OVH, they suggest we use sdns1.ovh.net or sdns2.ovh.net as our secondary DNS servers, which is great and it works fine and everything. The thing I'm wondering is how do the servers figure out which records to send? The idea…
Smudge
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Subdomain on another host (another IP, another provider)

Let's say my main domain is domain.net and i'm using it on a Media Temple (gs) server. I have my blog on the subdomain blog.domain.net Now I want to host my blog on my new VPS from Linode. So, I need to keep domain.net on Media Temple and…
Thiago Belem
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Nameserver Issue?

I have a domain registered with active-domain.com and yesterday I changed my nameservers to my host, but then I decided to switch my host at the last minute and changed them again. Now, 24 hours or so later, the site will still occasionally pull up…
Rob
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Some ISPs unable to resolve my subdomains

I have a COM domain with several subdomains. These subdomains have CNAME records pointing to ghs.google.com (they point to different Google App Engine apps). These have been in use with no problem for a few months. Recently, however, I've started…
David Underhill
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What services require properly configured PTR records?

I manage a few DNS servers (Bind9, Windows Server 2008 R2) that are used internally. I have always taken the time to make sure that the correct corresponding PTR records were configured for Reverse DNS Lookups, because it 1) seemed more complete to…
user62491
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change ip to dns in /etc/hosts on Ubuntu 11.04

in ubuntu 11.04, i'm trying to change dns to force it to point to another server let's assume the domain name is www.mysite.com and the ip 96.32.66.xx i changed /etc/hosts but when i open the browser it dosen't work. if i ping 96.32.66.xxx it…
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