DHCP, Dynamic DNS, and IPv6

[David W. Hankins]

On Thu, Aug 28, 2008 at 07:51:23AM -0700, David W. Hankins wrote:
> ISC DHCPv6 does support the DHCPv6 FQDN option and Dynamic DNS
> Updates, configuration is precisely the same as with DHCPv4.  As I
> looked at the sources recently, there is one wrinkle (bug); when the
> AAAA's expire, it will remove the last DHCID if there are no more
> AAAA's (assigned by other servers).  It needs to check that there are
> also no more A's.  Repairing this is a SMOP, look to
> "^ddns_remove_fwd" in common/dns.c, and the section of code headed by
> "A RR does not exist".  Simply make this two explicit PREREQs for no
> A and no AAAA (opcode = NXRRSET), rather than one for the prescribed
> "ddns_address_type".

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.

-- 
Ash bugud-gul durbatuluk agh burzum-ishi krimpatul.
Why settle for the lesser evil?	 https://secure.isc.org/store/t-shirt/
-- 
David W. Hankins	"If you don't do it right the first time,
Software Engineer		     you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins