Standardizing on IDNA 2003 in the URL Standard

Andrew Sullivan ajs at
Fri Aug 23 17:23:10 CEST 2013

On Fri, Aug 23, 2013 at 12:19:02PM +0200, Mark Davis ? wrote:

>    registries disallow non-IDNA2008 URLs. I say URLs, because the registries
>    need to not only disallow them in SLDs (eg http://☃.com), they
> *also*need to forbid their subregistries from having them in Nth-level
> domains
>    (that is, disallow http://☃ =

This isn't something that they do today.  Indeed, there is nothing to
prevent a site from putting a label there that is just the relevant
raw UTF-8 bits.  The thing we use to avoid this is "it doesn't work".

In a different context, Dennis Jennings has been arguing for similar
rules as well, and it's a mistake.  We do not _want_ deep labels to
have to follow the same rules as for names at the second or third
levels.  For instance, we want top-level domain registries to permit
only LDH-labels (of some sort, including A-labels).  But LDH-labels
don't include underscores.  Does that mean that we'd want to ban (say)
SRV or DKIM TXT records?  I think not.

The DNS is not a global database with consistent policy.  That's a
deep down design feature, not a bug, and if people think that it
_needs_ to have a consistent policy, then we need a different naming



Andrew Sullivan
ajs at

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