DNS Update failing on AAAA

[Eustace, Glen]

> I think the behaviour is correct given the 'update policy' which it
> intends to implement.
> 
> That is, plonking down an A record where there's a AAAA but no DHCID
> is equally as damaging as plonking down an A record where there's
> already an A, or any other records exist.
> 
> Consider:  You could have added a matching DHCID.

I disagree.

Whilst IPv4 and IPv6 may be transported over the same infrastructure
they are distinct protocols. We have no solution for supporting dynamic
IPv6 DHCP (not provided in ISC dhcpd - hint) so we are having to
statically assign the addresses both in the DNS and on the client.

The allocation of an IPv4 lease has nothing to do with the IPv6
configuration on the client and should not be impacted by any IPv6
attributes in the DNS either.

I believe that the test should be specific, if an 'A' exists and no
DHCID - fail, if the DHCID matches - pass, if no 'A' and no DHCID -
pass. The presence of the AAAA should have no impact on the clients use
of IPv4.

Glen