Impact of Punycode

Shawn Steele Shawn.Steele at
Thu Mar 25 19:33:41 CET 2010

I’m NOT arguing changing or replacing IDN.  I’m saying that it isn’t easy to fix ALL of the client apps.  We made it “easy” (sort of) for the DNS side, but at the expense of confusion on the client side.

I am suggesting that for Email, the EAI approach is less problematic.  Yes, e-mail servers will need updated, but there will be less long-term confusion.


From: idna-update-bounces at [mailto:idna-update-bounces at] On Behalf Of Vint Cerf
Sent: Poʻahā, Malaki 25, 2010 11:28 AM
To: Shawn Steele
Cc: idna-update at
Subject: Re: Impact of Punycode

shawn, if you have a better strategy maybe it is timely to start another BOF. In the past attempts to do IDN, the client-only approach has been adopted because of the difficulty of changing all the servers and resolvers. If enough simplification would result from such a mandate, perhaps it is at least worth looking at fully. My recollection is that some people tried for a new Class of DNS record other than IN because it could have different properties (that would have to be known to the servers and the resolvers, of course). That approach did not gain consensus.


On Thu, Mar 25, 2010 at 2:18 PM, Shawn Steele <Shawn.Steele at<mailto:Shawn.Steele at>> wrote:
> 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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