[dns-operations] check if a domain has been registered via DNS

[Viktor Dukhovni]

> On Apr 28, 2017, at 1:11 PM, Robert Edmonds <edmonds at mycre.ws> wrote:
> 
> No?
> 
>    de.                     172800  IN      NS      a.nic.de.
>    de.                     172800  IN      NS      f.nic.de.
>    de.                     172800  IN      NS      l.de.net.
>    de.                     172800  IN      NS      n.de.net.
>    de.                     172800  IN      NS      s.de.net.
>    de.                     172800  IN      NS      z.nic.de.
>    ;; Received 353 bytes from 192.203.230.10#53(e.root-servers.net) in 8 ms
> 
>    com.de.                 86400   IN      NS      ns1.centralnic.net.
>    com.de.                 86400   IN      NS      ns2.centralnic.net.
>    com.de.                 86400   IN      NS      ns3.centralnic.net.
>    com.de.                 86400   IN      NS      ns4.centralnic.net.
>    ;; Received 125 bytes from 81.91.164.5#53(f.nic.de) in 114 ms

I was/am aware of the "com.de" delegation from "de."

I choose to not make much of a distinction between "uk." and "co.uk.",
or "de." and "com.de.".  These are much the same sort of beast, 1LD
and 2LD public suffixes.  If we we want to be strict about limiting
the discussion to 1LDs, then my only examples are nic.co, domain.co,
jobs.lk, and topjob.lk.

I should note that my sample is artificially constrained, I only collect
data on domains with DS records (or validated CNAMEs to such domains).
There are likely (many) others that I did not test or did not record.

-- 
	Viktor.