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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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Anycast DNS -- how do you deal with TCP DNS requests?

Let's assume I have setup a pair of anycasted DNS servers on my internal network using bird and they're just talking OSPF to my core routers. I've found this on the internet and made it happen. If I setup one to have a higher cost path than the…
chris
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Caching DNS returns SERVFAIL for NS record, but dig +trace disagrees?

This question is similar, but doesn't elaborate on the confusing case of a why a NS record cannot be obtained. One of our caching DNS environments (RHEL 5.8, BIND 9.3.6-20.P1.el5_8.4) has ceased to return any useful data at all for a zone. Usually…
Andrew B
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How to forward missing DNS names of an existing zone in Windows DNS server?

I have setup DNS records for a public domain (say example.com) in my public DNS provider. Among the records, there are some A records of the type *.production.code.example.com that point to a specific public IP. I need to setup local DNS in my…
kosfar
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How to avoid messages rejection because of DMARC when sent through Gmail alias?

Many people add ' another email address as alias ' for their Gmail accounts - talking here about public Gmail not Google Apps - and they may use Gmail server not their domain servers as SMTP with the ' Treat as an 'alias' setting '. While DMARC not…
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Using Microsoft DNS to respond based on requesting subnet

In our enterprise Windows Active Directory environment, we have some 50+ subnets scattered across a large geographical area. We have a system at each site that supports the site by providing a central drivers store, a central software store, SEP…
Kasius
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Cannot run OpenVPN on port 53 (DNS Stops Working)

So I'm trying to get OpenVPN to work on port 53 - sadly this isn't working. I used IP tables to map port 53 to port 1194 (standard OpenVPN port) Here's what I run to do this: iptables -t nat -A PREROUTING -p udp --dport 53 -j REDIRECT --to-port…
Matthew 'mandatory' Bryant
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Windows 7 is skipping the primary DNS server and moving straight to the alternate DNS server

I'm running into an odd issue with a number of Windows 7 machines on my network. These machines are currently configured to use a local DNS server, 192.168.1.42, as their primary DNS server. Google's public DNS, 8.8.8.8, is configured as an…
James Westbury
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Does MX Records have anything to do with outbound email?

I'm really confused about the MX Records and generally with email. I've set up Haraka SMTP server for outbound email delivery because I need to send sign up validation emails. If I don't want to receive emails just to send them, do I need to setup…
Adam Halasz
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MX Backup service

What suppliers can you recommend, that provide an MX backup service?
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Setting up CloudFront CDN on a cookieless root domain

I have recently set up an AWS S3 bucket for my site's static content, along w/ a CloudFront distribution for my CDN. I have this working using a sub-domain. However, after running YSlow, I realized that cookie data is still getting passed to my…
Jerad Rose
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Statically mirroring a heavy trafficked site, CloudFlare as DNS

I run a fairly heavy trafficked website and due to some unfortunate incidents the machines that are in my cloud at Linode went down. And I have only a single Load Balancer machine exposed to the outside world (one IP). Also my site is a candidate…
Quintin Par
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What are all the possible causes of the "An Active Directory Domain Controller (AD DC) for the domain ..." error message?

Earlier I was having issues connecting one of my workstations (client) to my domain, and I thought it was because the domain was not in my possession yet (reference: this question). But, due to the answer I'm led to believe that there is something…
michael
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Achieving Five Nines

I am building a web application where uptime is key. I understand that 100% uptime is not realistic but I would like to achieve five nines. I'm unsure as to the most prudent way to accomplish this. My preliminary plan was to have the web app running…
user102878
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How do I set up a reverse zone file?

I have this zone file in bind: $TTL 86400 mysite.net. IN SOA ns1.mysite.net. admin.mysite.net. ( 2006012008 86400 3600 604800 86400 ) mysite.net. IN NS …
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Does a domain's Glue Records get transferred when I transfer the domain to another registrar?

I have a domain, call it DOMAIN.NET, which is an Internet service provider. DOMAIN.NET has Glue Records that I put in via the existing registrar, which enable the client domains like FOO.COM, BAR.COM, BAZ.COM, etc. to use NS1.DOMAIN.NET and…
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