Arbitrary DDNS removal after DHCPv6 renew

[Scott Comstock]

All,

I've found an interesting issue.  Just before the weekend, I brought
up a CentOS 6.2 box (kelutral), which was assigned IPv4 and IPv6
addresses by the DHCP server (v4.2.3) along with dynamic DNS entries
for each.  However, over the weekend, the DHCPv6 server inexplicably
deleted the DDNS entries after kelutral attempted to renew its IPv6
address:

===
Jun 15 14:04:49 wilykat dhcpd: Solicit message from
fe80::224:8cff:fe9d:471e port 546, transaction ID 0xEA19F500
Jun 15 14:04:49 wilykat dhcpd: Picking pool address 2001:470:1f07:2f0::224
Jun 15 14:04:49 wilykat dhcpd: Sending Advertise to
fe80::224:8cff:fe9d:471e port 546
Jun 15 14:04:49 wilykat dhcpd: Request message from
fe80::224:8cff:fe9d:471e port 546, transaction ID 0x49DFC200
Jun 15 14:04:49 wilykat dhcpd: Sending Reply to
fe80::224:8cff:fe9d:471e port 546
Jun 15 14:04:49 wilykat dhcpd: Added new forward map from
kelutral.ipv6.scottcomstock.net. to 2001:470:1f07:2f0::224
Jun 15 14:04:49 wilykat dhcpd: Added reverse map from
4.2.2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.f.2.0.7.0.f.1.0.7.4.0.1.0.0.2.ip6.arpa.
to kelutral.ipv6.scottcomstock.net.

(later...)

Jun 17 02:04:49 wilykat dhcpd: Renew message from
fe80::224:8cff:fe9d:471e port 546, transaction ID 0x9C386C00
Jun 17 02:04:49 wilykat dhcpd: Sending Reply to
fe80::224:8cff:fe9d:471e port 546
Jun 17 02:04:49 wilykat dhcpd: Removed forward map from
kelutral.ipv6.scottcomstock.net. to 2001:470:1f07:2f0::224
Jun 17 02:04:49 wilykat named[2747]: zone ipv6.scottcomstock.net/IN:
Transfer started.
Jun 17 02:04:49 wilykat dhcpd: Removed reverse map on
4.2.2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.f.2.0.7.0.f.1.0.7.4.0.1.0.0.2.ip6.arpa.
Jun 17 02:04:49 wilykat named[2747]: zone ipv6.scottcomstock.net/IN:
transferred serial 2012060060
Jun 17 02:04:49 wilykat named[2747]: zone
0.f.2.0.7.0.f.1.0.7.4.0.1.0.0.2.ip6.arpa/IN: Transfer started.
Jun 17 02:04:50 wilykat named[2747]: zone
0.f.2.0.7.0.f.1.0.7.4.0.1.0.0.2.ip6.arpa/IN: transferred serial
201206145
Jun 17 02:04:54 wilykat named[2747]: zone ipv6.scottcomstock.net/IN:
notify from 2001:470:1f07:2f0::4#15128: zone is up to date
===

(fe80::224:8cff:fe9d:471e is kelutral's link-local address)

The address hasn't changed; as of this morning it's still
2001:470:1f07:2f0::224.  The machine was up all weekend; why would the
DHCP server have dropped the DDNS entry?

Thanks,
-Scott