[idn] Do we need ACE?

[Dan Oscarsson <Dan.Oscarsson@trab.se>]

John Klensin have written a draft for using a separate class to handle
IDNs. This to really separate the IDN world from the old.

As software following the current rules on what characters are
allowed in a host name should reject queries and responses when
an invalid host name is used, could we get this separation between
old and new by just using UTF-8 in DNS?

If the DNS queries and responses having forbidden characters in host names
are ignored/rejected, an old software will not be able to lookup or
receive records with non-ASCII host names. I know that at least
some resolver routines (it is all in the client, DNS does not forbid
the characters) rejects PTR responses with non-ASCII in them.
If it is like this, the new IDN world will be hidden for all old clients.
This would the result in the old clients will not get any host names
through DNS that they cannot handle. Of course they will still get
invalid names by cut and past between new and old applications, but that
problem we have in all cases.
This way we would get the separate IDN and old DNS world without a new
class, instead we would get it because old software will see IDNs as
invalid.

But I have the feeling that most do not want the break with the old, instead
they want the old software to in some way to be able to handle IDNs too?
Though with all the mess it sometimes feels like, a break with the old
might be better.

   Dan