Subject: dhcp-dns: sending deletes

From: "David Erdmann" <[email-masked]>
Date: Thu, 2 Sep 1999 11:09:59 -0400 (EDT)

I am looking over the dhcp-dns-10 draft and am wondering about the 
following text:

"If a server detects that a lease on an address that the server leases
   to a client has expired or has been released by the client, the
   server SHOULD delete the PTR RR which it associated with the address
   via DNS Dynamic Update. In addition, if the server added an A RR on
   behalf of the client, the server SHOULD also delete the A RR. The
   deletion MUST follow the procedures described in Section 3.4.

   If a server terminates a lease on an address prior to the lease's
   expiration time, for instance by sending a DHCPNAK to a client, the
   server SHOULD delete the PTR RR which it associated with the address
   via DNS Dynamic Update. In addition, if the server took responsibil-
   ity for the client's A RR , the server SHOULD also delete that A RR.
   The deletion MUST follow the procedures described in Section 3.4."

If the DHCP server did NOT add the A RR on behalf of the client what is
the expected behavior...I assume that it the DHCP server MAY delete that
A RR.

-Dave

----------------------------------
Dave Erdmann
Nortel Networks, NetID Group
mailto:[email-masked]

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From: Bill Sommerfeld <[email-masked]>
Date: Thu, 2 Sep 1999 13:16:50 -0400 (EDT)

> the expected behavior...I assume that it the DHCP server MAY delete that

Hmm.  I'd argue that if the DHCP service didn't put the RR there, it
has no business trying to delete it.

						- Bill

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From: Mark Stapp <[email-masked]>
Date: Thu, 2 Sep 1999 14:51:48 -0400 (EDT)

Dave,

Thanks for the feedback. I agree with you - in fact I'd go so far as to say
that if the DHCP server was not responsible for the A RR, it SHOULD NOT
delete it. I guess I thought that the conditional, "if the server took
responsibility for the client's A RR", was clear enough. Is the "took
responsibility" phrase too vague? I was thinking of two possibilities: that
the server added the A RR, and retained responsibility; or that the client
added the A RR, but the server was subsequently configured to take
responsibility for it (perhaps because an administrator got tired of A RRs
that matched clients who had gone away but been unable to remove their
dynamic A records.)

That's where I'd draw the line a little differently than Bill Sommerfeld
suggests in his reply. Some vendor may want to supply, and some
administrator may want to use, a DHCP server that *can* be configured to
allow clients to perform their own A updates, but which can also 'sweep up'
after them when their leases end - just in case. Given appropriate
credentials, and following the rules for performing deletes in 3.4.3, that
should work.

I tried to use wording like "took responsibility for the record" rather
than "added the record" as a way of making that distinction clear, but I
see that I didn't quite do that everywhere. Would it be helpful if I tried
to add some more words about this, perhaps at the beginning of section 3
where the "there are lots of possible policies" language is?

Thanks,
Mark