Hi, > On 7. Jul 2026, at 05:02, Jan Schaumann > <[email protected]> wrote: > > Erik Nygren <[email protected]> wrote: > >> As the DNS is the primary mechanism for translating from hostnames to >> IP addresses, it is a logical place to signal that endpoints are >> IPv6-only. It is thus also a logical place to signal that legacy >> endpoints supporting IPv4 are being deprecated. This specification >> introduces two SvcParams for SVCB-compatible RR types that signal >> IPv6-only endpoints (ipv6only) as well as deprecated endpoints >> (deprecated). >> >> The "ipv6only" SvcParam touches on V6OPS and HAPPY. I see this not as >> something we desperately need now/yet but as something we will want in a few >> years and thus should standardize sooner so that the implementations are >> there >> for when we need it. > > I have to admit that my experience so far with the > adoption of SVCB and HTTPS records makes me wonder > whether this will be a practically useful approach. > > Right now, browsers[1] are racing all three lookups > (HTTPS, A, and AAAA), and any findings from HTTPS > records are, if supported or implemented by browsers > at all, advisory at best. > >> From a browser (or happy eyeballs) perspective, that > makes sense: waiting for the HTTPS result before then > having to possibly do another two sequential lookups > leads to a bad user experience. > > But that also means that the "ipv6only" param would > not be particularly useful in practice so long as > browsers still race the A and AAAA lookups. I > anticipate browsers will continue to do that for as > long as IPv4 and IPv6 records are both widely > used[2]. > > > As for the "deprecated" param, I also don't quite know > what I am to do with it when I observe it, given that > I "SHOULD NOT provide special treatment". > > I fear that the idea behind the proposal ("make it > easier for people to migrate off IPv4 and to > IPv6-only") is a solution in search of a problem: I'm > not convinced the technical ability to migrate is > hampered by the lack of a method to signal to clients > your intention; what's missing is the intention to > migrate.
I have the following problem every day: Some developers want to test for IPv6 regressions and would prefer not to disable IPv4 on their laptops to enforce this. Also, it helps you to find IPv6 performance regressions that would be masked by Happy Eyeballs otherwise. Having that said… I am not sure whether there is a need for both mechanisms. The IPv6-only parameter is rather stating the obvious … if set up correctly, pointing to a backend without IPv4 and bumping up priority does the same. For the deprecated, I see a value: Notify users they are In legacy/fallback mode. If used sparsely and only enabled in clients of people who understand it, it would be a great debugging tool. AVE! Philipp > As an entirely naive alternative, I would expect an > IPv6-only service to be one that has only AAAA records > (and includes ipv6hint params, but no ipv4hint params > in any SVCB records, which browsers may or may not > race at the same time). > > Perhaps it would be useful to include in the draft a > brief description why that is insufficient and whether > the anticipation is that browsers will (eventually) > _not_ race HTTPS and A/AAAA lookups but _only_ use > HTTPS lookups (or use those as blocking prior to any > A/AAAA lookups). > > Sorry, this got longer than I initially set out to. > > -Jan > > [1] And it really is browsers we have to care about > here, since those are effectively setting much of the > direction of the Web. > > [2] Which, in turn, I anticipate to remain the case > throughout the rest of my lifetime, at least. > > _______________________________________________ > v6ops mailing list -- [email protected] > To unsubscribe send an email to [email protected] _______________________________________________ DNSOP mailing list -- [email protected] To unsubscribe send an email to [email protected]
