Impact of Punycode

Shawn Steele Shawn.Steele at
Thu Mar 25 19:18:01 CET 2010

> Nothing about IDNA200x should have any effect of any sort on any DNS server
> that "handled UTF-8".  DNS labels are not restricted to ASCII, and never have
> been: they're octets.  The LDH rule is not a "DNS restriction".  It's an effect of
> the way the hostname syntax got used inside the DNS.

IDN doesn't impact "DNS".  It impacts people using domain names.  Now the APPLICATIONS have to have domain knowledge about a protocol that means very little to the application.  For example, if you make an http request, the xn-- name can get into the http request.  Certainly the IDNAxxxx docs say nothing about http requests.  What's a web server to do if it gets a UTF-8 request?  A Punycode request?

In making things "simple" for DNS, we made things very hard for the rest of the system.

Sort of way off topic for an IDNA list, and I'm not suggesting that we abandon IDNA, but I'd MUCH rather see the EAI approach than experience the same problems with other protocols.  

- Shawn

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