Some reading on IRIs and IDNs

[Stephane Bortzmeyer]

On Mon, Dec 14, 2020 at 11:46:49AM +0100,
 Philip Linde <linde.philip at gmail.com> wrote 
 a message of 45 lines which said:

> but different systems as in different name resolution systems.

Yes.

> café.mozz.us in your tests probably always resolved via DNS, but if
> you had a café.local mDNS name or "café" in your hosts file you
> might not be able to use IDN. I don't know about the hosts file, but
> mDNS for example uses UTF-8 encoded names directly.

I just tested with a Debian box and it seems getaddrinfo (both from a
Python program and from a C one, ping), requires the name in
/etc/hosts to be present in Punycode form (A-label).

The good news is that the Python program does not have to do
punycoding itself, it is handled automatically by the standard
library.