Subject: RE: [dhcwg] Issues in DDNS-DHCP interaction drafts

From: "Cosmo, Patrick" <[email-masked]>
Date: Fri, 6 Jun 2003 11:31:26 -0700

I have found some minor issues with the
<draft-ietf-dhc-ddns-resolution-05.txt>, I apologize if they have already
been brought up. 

In particular, this statement in section 5. (DNS RR TTLs) on page 5:

"The RR TTL on a DNS record added for with a DHCP lease SHOULD NOT exceed
1/3 of the lease time, and SHOULD be at least 10 minutes."

1. This sentence has some bad grammar ("for with" : ... record added for
with a DHCP lease ...). 

2. The statement is contradictory if the lease time is less than 30 minutes.
When the lease time is less than 30 minutes, which suggestion takes
precendence? : min. 10 minutes, or max or 1/3 lease time?

3. The section seems intended to suggest a reasonable TTL for these records,
but doesn't seem to pull through or suggest much of anything (IMHO) other
than "it should be a function of lease time, and it should be configurable".

Patrick Cosmo
 
Senior Product Engineer
Incognito Software Inc
Vancouver: (604) 688-4332 ext: 254
Toll-Free: 1-800-877-1856
http://www.incognito.com

-----Original Message-----
From: Ralph Droms [mailto:[email-masked]]
Sent: Thursday, June 05, 2003 7:36 PM
To: [email-masked]; [email-masked]
Subject: [dhcwg] Issues in DDNS-DHCP interaction drafts

The following drafts have passed WG last call:

[1] A DNS RR for Encoding DHCP Information (DHCID RR)
    <draft-ietf-dnsext-dhcid-rr-06.txt> 

[2] The DHCP Client FQDN Option 
    <draft-ietf-dhc-fqdn-option-05.txt>

[3] Resolution of DNS Name Conflicts Among DHCP Clients 
    <draft-ietf-dhc-ddns-resolution-05.txt>

Several issues regarding these drafts have been identified
during the AD review prior to IESG review for Proposed
Standard status.  I will initiate discussion threads on
each of these issues later today with e-mail to both
the dhcwg and namedroppers mailing lists.  Please respond
just to the dhcwg mailing list to avoid duplicate postings...

- Ralph

_______________________________________________
dhcwg mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/dhcwg

---

From: Ralph Droms <[email-masked]>
Date: Fri, 6 Jun 2003 15:11:35 -0400 (EDT)

DDNS-DHCP issue:

   The RR TTLs need careful attention so that it never exceeds the
   expiration time of the lease on the associated address.

This issue was anticipated by Patrick Cosmo:

---

From: Mark Stapp <[email-masked]>
Date: Fri, 06 Jun 2003 15:48:38 -0400

I've replied to Patrick; I'm not quite sure what more to do with issue [6].

The draft recommends using a ttl that's a fraction of the lease time, and 
recommends removing rrs promptly when the lease expires. There have been at 
least a couple of exchanges about this over the years, and the conclusion 
has always been that it's not possible to come up with a single set of 
values that are appropriate in every situation. Also, it's not possible to 
compel updaters to perform additional updates to 'back down' rrs' ttls as a 
lease approaches its expiration - that'll kill the dns server. As I noted 
in the other email I sent, the recommendations that are in the draft are 
the most up-to-date ones that I've been offered.

We do have quite a bit of deployment experience with dhcp updates to dns, 
and this has not been an issue, as far as I can recall. I also don't recall 
any email to the wg indicating that this has been an issue in anyone else's 
experience. If someone has followed these recommendations and has found 
problems with them, then by all means let's come up with better 
recommendations.

-- Mark