How do I find the authoritative name-server for a domain name?

Question

And for extra credit - Is it possible to find the origins of conflicting DNS records?

Answer 1

An easy way is to use an online domain tool. My favorite is Domain Tools (formerly whois.sc). I'm not sure if they can resolve conflicting DNS records though. As an example, the DNS servers for stackoverflow.com are

  NS51.DOMAINCONTROL.COM
  NS52.DOMAINCONTROL.COM

Answer 2

You'll want the SOA (Start of Authority) record for a given domain name, and this is how you accomplish it using the universally available nslookup command line tool:

command line> nslookup
> set querytype=soa
> stackoverflow.com
Server:         217.30.180.230
Address:        217.30.180.230#53

Non-authoritative answer:
stackoverflow.com
        origin = ns51.domaincontrol.com # ("primary name server" on Windows)
        mail addr = dns.jomax.net       # ("responsible mail addr" on Windows)
        serial = 2008041300
        refresh = 28800
        retry = 7200
        expire = 604800
        minimum = 86400
Authoritative answers can be found from:
stackoverflow.com       nameserver = ns52.domaincontrol.com.
stackoverflow.com       nameserver = ns51.domaincontrol.com.

The origin (or primary name server on Windows) line tells you that ns51.domaincontrol is the main name server for stackoverflow.com.

At the end of output all authoritative servers, including backup servers for the given domain, are listed.

Answer 3

I have a DNS propagation tool designed to answer these kind of questions.

Source is released under the AGPLv3.

(Yes, the interface is rather basic at the moment :) )

You could also find out the nameservers for a domain with the "host" command:

[davidp@supernova:~]$ host -t ns stackoverflow.com
stackoverflow.com name server ns51.domaincontrol.com.
stackoverflow.com name server ns52.domaincontrol.com.

Answer 4

You can use the whois service. On a UNIX like operating system you would execute the following command. Alternatively you can do it on the web at http://www.internic.net/whois.html.

whois stackoverflow.com

You would get the following response.

...text removed here...

Domain servers in listed order: NS51.DOMAINCONTROL.COM NS52.DOMAINCONTROL.COM

You can use nslookup or dig to find out more information about records for a given domain. This might help you resolve the conflicts you have described.

Answer 5

On *nix:

$ dig -t ns <domain name>

Answer 6

The term you should be googling is "authoritative," not "definitive".

On Linux or Mac you can use the commands whois, dig, host, nslookup or several others. nslookup might also work on Windows.

An example:

$ whois stackoverflow.com
[...]
   Domain servers in listed order:
      NS51.DOMAINCONTROL.COM
      NS52.DOMAINCONTROL.COM

As for the extra credit: Yes, it is possible.

---

aryeh is definitely wrong, as his suggestion usually will only give you the IP address for the hostname. If you use dig, you have to look for NS records, like so:

dig ns stackoverflow.com

Keep in mind that this may ask your local DNS server and thus may give wrong or out-of-date answers that it has in its cache.

Answer 7

I did what Antti Sykäri suggested. I got the following result.

RQD5:~ jon$ nslookup
> set querytype=soa
> r******s.co.uk
Server:    192.168.2.1
Address:   192.168.2.1#53

Non-authoritative answer:
r******ys.co.uk
        origin = ns1.turbodns.co.uk
        mail addr = hostmaster.r******s.co.uk
        serial = 2008090115
        refresh = 28800
        retry = 7200
        expire = 604800
        minimum = 600

Authoritative answers can be found from:
> 

The name server listed as origin is not what I expected to see there and is hopefully the source of the erroneous records.

Should I be concerned that I do not have Authoritative answers?

Answer 8

There are a number of free DNS tools out there that can check anything like this for you, (as long as you already have an internet connection of course).

My favourite at the moment is: http://mydnstools.info

Answer 9

You used the singular in your question but there are typically several authoritative name servers, the RFC 1034 recommends at least two.

Unless you mean "primary name server" and not "authoritative name server". The secondary name servers are authoritative.

To find out the name servers of a domain on Unix:

  % dig +short NS stackoverflow.com
 ns52.domaincontrol.com.
 ns51.domaincontrol.com.

To find out the server listed as primary (the notion of "primary" is quite fuzzy these days and typically has no good answer):

% dig +short  SOA stackoverflow.com | cut -d' ' -f1
ns51.domaincontrol.com.

To check discrepencies between name servers, my preference goes to the old check_soa tool, described in Liu & Albitz "DNS & BIND" book (O'Reilly editor). The source code is available in http://examples.oreilly.com/dns5/

% check_soa stackoverflow.com
ns51.domaincontrol.com has serial number 2008041300
ns52.domaincontrol.com has serial number 2008041300

Here, the two authoritative name servers have the same serial number. Good.

Answer 10

Unfortunately, most of these tools only return the NS record as provided by the actual name server itself. To be more accurate in determining which name servers are actually responsible for a domain, you'd have to either use "whois" and check the domains listed there OR use "dig [domain] NS @[root name server]" and run that recursively until you get the name server listings...

I wish there were a simple command line that you could run to get THAT result dependably and in a consistent format, not just the result that is given from the name server itself. The purpose of this for me is to be able to query about 330 domain names that I manage so I can determine exactly which name server each domain is pointing to (as per their registrar settings).

Anyone know of a command using "dig" or "host" or something else on *nix?

Answer 11

You can also use registrarwhois.info, it is without captcha!