"SRV-Style" labels and "IDN"
Mark_Andrews at isc.org
Thu Apr 2 22:55:29 CEST 2009
In message <49D4A23B.2060205 at alvestrand.no>, Harald Alvestrand writes:
> Mark Andrews wrote:
> > In message <8BC845943058D844ABFC73D2220D4665081E4704 at nics-mail.sbg.nic.at>,
> > exander Mayrhofer" writes:
> >> Hi,
> >> I'm currently reading through the idnabis-Documents, and didn't find a
> >> clear answer to the following issue:
> >> 188.8.131.52 of draft-ietf-idnabis-defs-08 defines an IDN as "name that may
> >> contain any mixture of NR-LDH-labels, A-labels, or U-labels". From what
> >> i read, that means that an IDN may not contain a "SRV-style" label,
> >> starting with an underscore. A few lines later, it is clarified that
> >> such a label is not an "Internationalized Label". There's no text about
> >> those labels in the definition of "IDN". Therefore, from the definition,
> >> the following example:
> >> _sip._tcp.<A-Label>.<tld>
> >> Would not be an IDN. My questions now, unless i have missed something:
> >> - Is my assumption correct that the example is not an IDN?
> >> - If it is not an IDN, what is it?
> > This reflects the mis-use of DOMAIN in IDN. In reality
> > IDN's should be named IHN's (International HOST Names).
> > LDH is a HOST NAME restriction, not a DOMAIN NAME restriction.
> > In general you won't ever enter _sip._tcp.<A-Label>.<tld>
> > in a application. You will enter <A-Label>.<tld> and
> > _sip._tcp will be prepended as part of the discovert process.
> > _sip._tcp.<A-Label>.<tld> is not a host name the same way
> > that _sip._tcp.example.net is not a host name but both are
> > legal domain names.
> > Mark
> we lost this fight (for rational use of "host" vs "domain" in the
> original IDN group back around 2000.
and it keeps coming back to bite us.
> in _sip._tcp.<A-label>.<tld>, it's rational to consider <A-label>.<tld>
> an IDN. I don't have a name for the assemblage.
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews at isc.org
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