Valid/invalid Label

[John C Klensin]

--On Friday, February 27, 2009 12:43 -0500 Andrew Sullivan
<ajs at shinkuro.com> wrote:

> On Fri, Feb 27, 2009 at 01:38:34PM +0330, Alireza Saleh wrote:
>> I think that a possible solution would be considering virtual
>> links  between one or some sections of Unicode and one or
>> some TLDs.  
> 
> I'm not convinced that "TLD" is the only important level,
> though. Surely it's entirely possible for someone to want (for
> instance) [U-label].blogspot.com.  No?  

Because of the conclusion that unlimited zone transfers were a
security risk and the implications of that conclusion, it is
hard to tell, but there is some evidence that there are far more
IDN label registrations at the third level and below than at the
second.  In particular,
   <local-name>.company.com
where <local-name> is language-specific and in the relevant
script, seems to be exceptionally common, as are structures like 
  <chinese-name>.<chinese-subdomain>.CN

While RFC1591 permits (and encourages) TLDs to make policies and
impose those policies recursively on the subdomain structure of
all registrants, I've aware of almost nowhere, outside
enterprise domains, where that is done.  And it would be
impossible to enforce in practice except reactively to
complaints.

    john