John,
take the following delegations in the parent zone example.
foo.example NS ns.bar.example
ns.foo.example AAAA 2001:0DB8:0000:000b::1
bar.example NS ns.foo.example
ns.bar.example AAAA 2001:0DB8:0000:000b::2
If you don’t return sibling glue a query for b.foo.example returns
a referral of
foo.example NS ns.bar.example
and a query for ns.bar.example returns a referral of
bar.example NS ns.foo.example
and the subsequent query for ns.foo.example returns a referral of
foo.example NS ns.bar.example
Returning sibling glue is not an optimisation.
> On 28 Jul 2021, at 10:47, John R Levine <jo...@taugh.com> wrote:
>
>>>> Just to make sure we're talking about the same thing, the definition of
>>>> sibling glue is glue from another zone delegated from the same parent.
>>>
>>> That's not what the example in 4.1 of the draft shows. It has foo.test
>>> depending on ns1.bar.test, so the server adds the A record for
>>> ns1.bar.test.
>>
>> It does actually.
>
> Oh, sorry, I misread your message.
>
>> "ns1.bar.test/A" is glue for "bar.test" (and sibling glue for "foo.test" in
>> that
>> example). It is returned by the servers for "test" in a referral for
>> "foo.test".
>>
>> Open to suggestions for more clarifying language.
>
> Unless I'm misunderstanding something, in the absence of sibling glue, the
> resolver would make a second request for ns1.bar.test, same as if it were
> ns1.bar.otherdomain, and it would get back a referral with the glue. It is
> just a performance tweak and I don't see why we should describe it as more
> than that.
>
> Regards,
> John Levine, jo...@taugh.com, Taughannock Networks, Trumansburg NY
> Please consider the environment before reading this e-mail. https://jl.ly
>
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Mark Andrews, ISC
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PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
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