On Thu, 4 Jul 2019 at 10:54, Matthijs Mekking <[email protected]> wrote:
> Matthew, > > > I would say they should rely on that. Why shouldn't they? Isn't our > > goal to get downstream servers to adopt the extension and do their own > > lookup? The server-side lookups and sibling records are bolt-ons to > > handle the adoption period. Remember, this record is geared toward > > customers of CDNs being able to do get similar behaviour to: > > www.example.com <http://www.example.com>. IN CNAME webfarm.cdn.net > > <http://webfarm.cdn.net>. > > at the apex of example.com <http://example.com>. That was the original > > problem we're trying to solve. I read your statement above about "the > > service they provide their customers" being about the CDN resolving > > webfarm.cdn.net <http://webfarm.cdn.net>, which most CDNs can already do > > within their own infrastructure. > > I am talking about DNS providers that perform CNAME at the Apex like > features: a customer goes to them and opts in to this feature. Such a > provider wants to make sure that it is providing the behavior the > customer expects and thus wants to make sure it hands out appropriate > addresses. > And "CNAME at the Apex like feeatures" is to hand out a CNAME and let the downstream server process that. It may include additional information from other zones it is authoritative for, but it doesn't do side-lookups. I think that's the behaviour we should be aiming for, and to do that some sort of "I understand ANAME" signal would allow the authoritative server to behave more like CNAME. > > Also what is wrong with an authoritative server already giving out more > optimal answers than just the ANAME and sibling address records? > Nothing, as long as it's not going to increase the time it takes to respond to the query. But, you didn't respond to my question. Let me rephrase it a bit: If the authoritative server knows the client understands ANAME, why would the authoritative server not assume that any additional data it supplies will be thrown away? I suggest that it would be wise for an authoritative server to assume that a client that understands ANAME will resolve its own ANAME and ignore any other data it gets. > > > Option #2 gets similar behaviour but at the cost of additional lookups. > > #3 and #4 don't work well in the presence of server farms. > > If addresses are in the response to the ANAME request there is no > difference in number of lookups between 2 and 3 I think. > Did you mean "lookups between 1 and 2"? I didn't say anything about the number of lookups required for 3. I think 3 and 4 are poor choices because they won't behave well with most server farms.
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