Lookup for reserved LDH labels
simon at josefsson.org
Thu Nov 8 10:09:29 CET 2012
Andrew Sullivan <ajs at anvilwalrusden.com> writes:
> On Wed, Nov 07, 2012 at 02:18:37PM +0100, Marcos Sanz wrote:
>> Then it will not be difficult for somebody to point us to the relevant
>> part in the spec that allegedly states that the lookup algorithm must fail
>> for reserved LDH-labels that are not XN-labels (e.g. "ad--acta"). I'd
>> really appreciate if somebody did that.
> Definitions document [RFC5890]. Putative U-labels with any of the
> following characteristics MUST be rejected prior to DNS lookup:
> o Labels that are not in NFC [Unicode-UAX15].
> o Labels containing "--" (two consecutive hyphens) in the third and
> fourth character positions.
> This is in section 5.4. Because of the way that section is
> structured, those labels are (at the time of evaluation given the
> protocol definition) actually putative U-labels.
Do you consider "ad--acta" a putative U-label?
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