Re: [DNSOP] [Ext] About key tags

[John Levine <[e-mail]>]

It appears that Shumon Huque  <[e-mail]> said:
>Yes, I agree. (Banning keytag collisions, if we are proposing that, is a
>protocol change.)
>
>Not also that DNSKEY set "coherency" is not really the issue. Even for a
>single signer they may be temporarily incoherent across nameservers because
>of normal change propagation delay. Multi-signer operations (for steady
>state or for a transitional state needed for DNS operator changes) can
>extend that period substantially. Collision avoidance is about the key
>generation process and the set of entities involved.

ISC has this nice page about how they dealt with keytrap:

https://www.isc.org/blogs/2024-bind-security-release/

About halfway down is a section "DNS scalability: the good, the bad,
and the ugly" which lists all the different ways a buggy or malicious
server might return stuff that is expensive to process, and then
points out that it is not a bug that the spec does not put hard limits
on any of them. As the Internet has evolved, people have come up with
clever ways to use the DNS, and the lack of hard limits enables it.
The obvious example is CNAME which was originally intended as a
temporary forwarding address but has evolved into all sorts of
mutlti-step cross-domain use without which CDNs would be impossible.

So of course we will describe all the ways we know to detect
and deal with scalability problems, but the solution (so far at
least) has never been to invent a new hard limit.

R's,
John