IDNA 2008 Question Re: "Confusable" Characters in Domain Names

John C Klensin klensin at
Fri Nov 5 23:35:05 CET 2010

--On Friday, 05 November, 2010 17:26 -0400 Andrew Sullivan
<ajs at> wrote:

> On Fri, Nov 05, 2010 at 02:17:01PM +0000, john daw wrote:
>> i'm not involved in the architecture of the Internet inany
>> way, as my original email might suggest. €.com, however,
>> ought to be "supported"as an existing domain name that is
>> currently in operation.
> Why "ought" it to be?  Under the standard domain name
> registration rules, "$.com" is not supported.
> You need to understand that the DNS evolved in an environment
> where there were existing names for hosts on the network.
> Those names were governed by the hostname rules, and those
> hostname rules were pretty restrictive.  So the DNS standard
> says, "If you want things to work well, you should use those
> hostname rules."  Those rules are the so-called LDH rules.
> And "$.com" doesn't meet the test.

One thing to add to this, which is that registries and
registrars were strongly advised, from the beginning, to not
register names containing characters other than letters, digits,
and the hyphen (with the first two groups expanded to cover
non-ASCII characters).  The reasons were essentially the ones
Andrew outlines.  If some of them permitted such registrations
anyway, and didn't pass the warning along, then it seems to me
that, if you have any complaints at all, they are with your
registrar or registry, not with the IETF.


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