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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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Azure web site not recognizing perfectly valid CNAME

I'm trying to add a custom domain to an Azure Web Site in standard mode. I've added the following DNS records: @ IN A 168.62.48.183 www IN CNAME ua-roadtosochi.azurewebsites.net. awverify …
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make dnsmasq ignore specific entries in /etc/hosts

I've set up a machine running dnsmasq, essentially serving its /etc/hosts file. However, there are specific entries which I want in that machine's /etc/hosts, but I don't want served. How can I make dnsmasq not serve them?
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Optimizing OS for HTTP requests

We make a lot of HTTP requests. Recently, we've started thinking about optimizations at the OS level to make more requests from a single machine. In order to check the performance of our OS, I've created a small benchmark to compare things on…
Julien Genestoux
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Apache: can ErrorLog be made to log also hostnames instead of IP addresses?

Having different Apache servers in a low-load intranet with almost only DHCP clients, we need to log hostnames instead of IP addresses. As the DHCP environment is quite dynamic, any later attempt to remap IPs to hostnames would most likely yield…
Christian
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Can a CNAME point to an NS record?

I have a subdomain NS record which looks like this: NS home ns1.nameserver.com NS home ns2.nameserver.com I'd like another subdomain super to point to the result of this NS name, but when I do: CNAME super home The name doesn't resolve. This is a…
Naftuli Kay
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Does the order of entries/record types matter in NSD/BIND zone config files?

I'm trying to streamline the addition of DNS records to an NSD install. It looks like it uses the same syntax as BIND so this question may be relevant to either. It seems like the convention I'm seeing in the current zone file is to separate the…
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Adding a DNS A record to a Win 2008R2 server from an Win 2008R2 server or Win7 via Powershell

I recently discovered that it is possible to simply automate DNS entry administration with a nice cmdlet: Import-Module DnsServer Add-DnsServerResourceRecordA -Name mail2 -IPv4Address 192.168.0.10 -ZoneName powershell.local I'd like to run this one…
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What would be correct setup procedure for PDNS server?

I am new to the world of DNS servers, but as a part of my current job I should do upgrade on our office network infrastructure. After looking at available options i decided to go with PowerDNS solution PDNS server. Mostly because of easy management…
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Domain name works with 3G connection but not on WiFi

I'm an administrator on two different SBS 2011 servers. Both servers are running MS Exchange. They are on different physical location, different hardware, different domains both internally and externally. The only thing they have in common is the…
Carl
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Exchange Server Address Resolving to Random String

I am running Exchange 2013 on Windows Server 2012 R2. When I add my exchange account to Outlook, it seems to work perfectly (sending/receiving email, syncing everything), but when I open the account settings it has the following set as the…
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Export all hosts from DNS Manager using Powershell

While I'm rather new to powerShell v3, there's some things I can do with it, however, one thing that has eluded me is how to pull all hosts listed in our DNS Manager (Server 2008 R2). I don't need to set or remove anything just have it query the…
Cozmo
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linux: shorter 'host' command output

I'm using dns to manage my virtual hosts. In order to do so I query my nameserver with the host command for certain values I need. For example: > host -t txt mycl1.vz mycl1.vz.myserver.de descriptive text "1026" but I only need 1026 as answer…
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Export/Import DNS Entries - Windows Server 2008 R2

I have a Windows 2008 R2 Server, Its primary role is to be a DNS server. I cant find how to import the previously "exported" DNS entries. To export I selected the server, clicked on Action->Export List. This created a text file of the entries. How…
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zone apex, alternative to A record?

I am running a small hosting service and from time to time I have a new user using cloudflare. To use cloudflare users 1) copy the DNS zone via the cloudflare interface 2) set cloudflare nameservers In the DNS zone there is a bunch of A records such…
wlf
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What would cause the hostname FQDN to repeat the suffix twice?

I have three new CentOS 6 servers that connect to a DHCP server to get an IP and to have DNS/rDNS setup to bind their FQDN and IP. Two of them are behaving as expected. One of them is appending the suffix twice. Instead of fulton.mydomain.com we get…
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