DHCP, Dynamic DNS, and IPv6

[Simon Hobson]

David W. Hankins wrote:

>Ohh, one more wrinkle.  It requires client support.
>
>For the A and AAAA records to coexist happily in your zone, the DHCPv4
>client has to send a particular client identifier, namely one with its
>DHCPv6 DUID incorporated.  Then your DHCP server (ISC DHCPv4 doesn't)
>has to support extracting this DUID and use only it to form the DHCID
>RRDATA (no IAID).
>
>Maybe we need to write more code on this topic sooner rather than
>later...I thought what we had was good enough to get through to later
>stages when 4.0.0 released.  Seems to me like maybe it isn't quite
>good enough.


So lets get this clear ...

1) The RFC says that the IP6 DHCP server cannot simply ignore all IP4 
stuff in the DNS.

2) And the IP6 DHCP isn't compatible with existing IP4 clients in 
it's handling of IP4 DNS unless you does 'special' things with the 
IP4 clients.

3) These 'special things' aren't supported on the IP4 clients - and 
probably NEVER will be on some of them with closed source.


I think something went wrong when this lot was being decided on. IMHO 
the IP6 stuff should have been written in such a manner that it could 
completely ignore the IP4 stuff. I can see the potential problems - 
such a two different clients with the same hostname, one gets the A 
record, the other gets the AAAA record, and so which gets accessed 
depends on what order a client does it's DNS lookups.

But when people start rolling out IP6, I don't think it's reasonable 
for that to require a complete overhaul of their IP4 DHCP setup for 
DDNS to work. The very minimum I would have expected would be for the 
V4 IP4 server to be capable of handling it's TXT records in a manner 
compatible with the IP6 server without having to modify clients - OR 
for the IP6 server to have a backwards compatibility mode to make it 
operate with an unmodified IP4 server.