Hi Mike,

On 12/3/25 20:36, Mike Bishop wrote:
Sorry for the delay, I've been away over US Thanksgiving. Further comments 
below, but I think the fact that this is being addressed in another WG draft 
satisfies the DISCUSS (though I'd recommend some expanded text and/or an 
informative reference here, even so).

Thanks! See below.

On 11/21/25 22:03, Mike Bishop wrote:
 >  > Is there a definition of how the Parental Agent "check[s] that ... 
updates ...
 >  > do not break the delegation"?
 >
 > No. I noticed that the (even vague) requirement was missing for CSYNC 
processing (as Paul pointed out), but there is a non-breakage requirement defined 
for CDS/CDNSKEY processing in RFC 7344 Section 4.1. It simply reads:
 >
 >      o  Continuity: MUST NOT break the current delegation if applied to DS
 >         RRset.
 >
 > My thinking was that it's reasonable to hold CSYNC to the same standard.
 >
 > [MB] That's frustrating. I agree that the same standard of not breaking 
things should apply here, but I'd like to see the process spelled out in a little 
more detail.

I agree it's frustrating that this was specified quite vaguely in RFC 7344, and 
also that it would be good if the process was spelled out in more detail. I'm 
not sure whether you meant to say that it should be spelled out here, or 
elsewhere.

Note, however, that the focus of this draft is requiring consistency across 
child authoritative nameservers. While non-breakage checks at the parent are a 
reasonable thing to do, they have nothing to do with that consistency 
requirement.

Ideally, the non-breakage requirement would, in my view, even apply to manual 
DS provisioning (but I guess that's debatable.)

There's another draft (draft-ietf-dnsop-ds-automation) which deals with DS 
provisioning aspects much more broadly. Among other things, it references the 
CDS consistency document as one thing that needs to be taken into account. 
Another thing is the non-breakage aspect, which is spelled out more explicitly 
there (Section 2.2.1). I think refining that definition there would be a better 
place, both scope-wise and for visibility.

If you agree, I'd appreciate your feedback that particular section in 
draft-ietf-dnsop-ds-automation.

[MB] I think it is a consistency issue, in that it's requiring consistency 
between the nameservers being proposed and the nameservers doing the proposing.

In the case of CDS/CDNSKEY, no nameservers are being proposed (that's CSYNC). 
But indeed, with trust chain updates signaled via CDS/CDNSKEY, continued 
validatability should be ensured. That's already mandatory today, but no 
details are specified.

I'll make sure this point gets considered via draft-ietf-dnsop-ds-automation.

I'm glad to see that it's already being considered. I've looked at Section 2.2.1 of that 
draft, and it's a good bit closer. I think what we ultimately want is something like 
"SHOULD synthesize the new NS, DS, and other records which would be applied if the 
update were accepted, then verify the existence and valid signature of the DNSKEY record 
on each nameserver referenced by an NS record in the new set."

That sounds reasonable to me.

I'm fine clearing the DISCUSS since it's being handled by another draft 
in-progress, but an informative reference might be useful. (It can't be 
normative without blocking this draft, but it's okay to informatively reference 
a strategy one could use to approach this requirement.)

When take that into account when I submit the updated revision.

 > or start failing due to inconsistencies;

That can't happen, because in case the CSYNC/CDS/CDNSKEY records used in the first sync 
were inconsistent, the update would not have been applied in the first case. (And if they 
were consistent, I'm not sure what you mean with "start failing due to 
inconsistencies".)

[MB] Consider a case where two nameservers publish CSYNC records adding a third 
NS record. However, that third nameserver publishes a conflicting CSYNC record. 
Once the update occurs, future update passes will find an inconsistent state. 
It might be nice to require that the target servers also publish 
CSYNC/CDS/CDNSKEY records which are consistent with the updates that cause them 
to receive the delegation. However, given that any inconsistency causes no 
change to occur, that's probably not critical — the system errs on the side of 
not making any further changes until the (new) nameservers all agree.

I see. CSYNC indicates that a change is desired, and the new nameservers would 
not immediately desire a change. Requiring them to publish a CSYNC RRset would 
be a semantics change, which is not in scope for this draft.

Best,
Peter

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