DHCP - DynDNS Interaction

[Yakov Rekhter <[e-mail]>]

Folks,

One of the issues raised during my presentation on the interaction
between DHCP and DynDNS Updates was the ability to expire individual
RRs.  As was observed, at the present momement DynDNS has no mechanisms
by which an entity that originates a DNS update could convey to a DNS
server the expiration time for the RRs that are updated.

For the PTR RRs the inability to convey the expiration time in the
DynDNS Updates could be overcomed by requiring a DHCP server to update
(delete) the appropriate PTR RRs once the server detects that the lease
on the IP addresses (associated with the PTR RRs) that the server
leased to its clients either expired or is released by the DHCP
clients.
 
For the A RRs a similar approach could be used when the A RRs are
updated by a DHCP server.

So, the only open issue is how to deal with a situation where a DHCP
client is responsible for updating its A RRs. Moreover, the problem
would occur only if the client would not be able to update (delete) its
A RR when the lease expires (this could happen if the client is turned
off at this moment). In this case it could be possible that the
client's FQDN would be associated with an IP address of some other
host. Observe that this would matter only when some other host
would try to contact the client (e.g., the client has some server
application).

I'd like to get an input from the DHC WG members whether the WG would
insist on requiring DynDNS Updates to provide a mechanism to convey the
expiration time (DynDNS doesn't have such a mechanism at the present
moment), or whether the WG would agree that I would document in the
DHCP-DynDNS Internet Draft the (potential) limitations imposed by the 
absence of such a mechanism in DynDNS, and we'll live with the limitations.

Yakov.