Re: [DNSOP] why did SRV care to avoid conflicts

Type comes AFTER name when looking up records.  Label name spaces are NOT type specific.  They are relative to the  RHS of the name they are part of.

There needs to be a registry of all label that can appear immediately to the left of a valid host name.
For each of those labels there needs to registries of what can appear to the immediate left of it.
For each of those labels there needs to registries of what can appear to the immediate left of it.
For each of those labels there needs to registries of what can appear to the immediate left of it.
For each of those labels there needs to registries of what can appear to the immediate left of it.
For each of those labels there needs to registries of what can appear to the immediate left of it.
For each of those labels there needs to registries of what can appear to the immediate left of it.

EACH of these registries are INDEPENDENT of type.

For SRV records only the first two levels matter.  For other types there are different numbers of registries involved.

> On 27 Mar 2018, at 9:07 am, Paul Vixie <paul@redbarn.org> wrote:
> 
> following klensin's observations that cross-rrtype conflicts cannot occur and that the only _necessary_ registry is of predefined labels with specific meanings _within each rrtype_, i've strugged to piece together my memory of why i wanted _ names for SRV at all.
> 
> it's because the meaning of RCODE=0 && ANCOUNT=00 was once different, or at least interpreted differently, by some stub resolvers, compared to RCODE=3. it had to do with temporary vs. permanent failures in e-mail, as i recall.
> 
> in any case today it's a non-issue. if i were specifying SRV today i would not bother with underbars, because TCP.REDBARN.ORG or UDP.REDBARN.ORG would not confuse any app that looks up AAAA (or A), since they would hear RCODE=0 && ANCOUNT=0, and fail hard.
> 
> -- 
> P Vixie
> 
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Mark Andrews, ISC
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