oddity with trubuiltpambula.com.au

[Karl Auer]

In the "Nameservers" section of the DNS management interface at a
hosting provider (webcity.com.au), we see three nameservers for the
above domain:

ns1.webcity.com.au (203.17.36.33)
ns2.webcity.com.au (203.17.36.4)
ns3.webcity.com.au (116.0.23.249)

However, when we query the DNS for the nameservers for this domain, we
get different answers:

kauer at kt:~$ dig +short trubuiltpambula.com.au ns
ns1.instanthosting.com.au.
ns2.instanthosting.com.au.

The two instanthosting nameservers returned have the same IP addresses
as ns1.webcity.com.au and ns2.webcity.com.au. And for completeness we
checked and there is also an instanthosting A record pointing to the
same IP as ns3.webcity.com.au:

kauer at kt:~$ dig +short ns3.instanthosting.com.au
116.0.23.249

We also get the two instanthosting nameserver names when we query any
of those webcity nameservers directly. For example:

kauer at kt:~$ dig +short trubuiltpambula.com.au ns @ns1.webcity.com.au
ns1.instanthosting.com.au.
ns2.instanthosting.com.au.

A trace shows an additional lookup occurring between the website
nameservers and the instanthosting nameservers being returned.

kauer at kt:~$ dig +trace trubuiltpambula.com.au ns
[...]
trubuiltpambula.com.au. 900 IN NS ns1.webcity.com.au.
trubuiltpambula.com.au. 900 IN NS ns2.webcity.com.au.
trubuiltpambula.com.au. 900 IN NS ns3.webcity.com.au.
[...]
;; Received 660 bytes from 65.22.197.1#53(r.au) in 51 ms
[...]
trubuiltpambula.com.au. 43200 IN NS ns2.instanthosting.com.au.
trubuiltpambula.com.au. 43200 IN NS ns1.instanthosting.com.au.
;; Received 102 bytes from 203.17.36.4#53(ns2.webcity.com.au) in 30 ms

Is there a good explanation for what's happening?

Yours mystifiedly, K.


-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://twitter.com/kauer389

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