[dns-operations] DDNS updates for 2.0.0.2.ip6.arpa to ns3.apnic.net

[Matthew Pounsett]

On Apr 24, 2014, at 10:28 , Chuck Anderson <cra at WPI.EDU> wrote:

> Has anyone seen bunches of machines on their network attempting to do
> DDNS updates to ns3.apnic.net for addresses in the 6to4 2002::/16
> block 2.0.0.2.ip6.arpa zone?  Should I be concerned?

ns3.apnic.net is the reverse DNS PTR for the actual MNAME of the 2.0.0.2.ip6.arpa zone.

% dig +short IN SOA 2.0.0.2.ip6.arpa.
ns-apnic.6to4.nro.net. dns-admin.apnic.net. 2004083706 7200 1800 604800 172800
% dig +short IN A ns-apnic.6to4.nro.net.
202.12.28.131
% dig +short IN PTR 131.28.12.202.in-addr.arpa.
ns3.apnic.net.

Do you have a 6to4 gateway in operation?   If there are misconfigured dhcp clients in your network, and you’re using addresses somewhere in 2002::/16 then it’s reasonable that you’d be seeing that traffic.