Re: [idn] impacted systems investigation

[D. J. Bernstein]

Nobody has presented any evidence of DNS caches having trouble with
UTF-8. Nobody has presented any evidence of DNS servers having trouble
with UTF-8. The discussion of server upgrades is divorced from reality.

There are some widely distributed DNS _client_ libraries that, in
violation of RFC 2181, reject DNS names containing unusual characters.
In particular, the version 8 libresolv gethostbyname() implementation
does this; look at gethostans(), maybe_ok(), res_hnok(), and res_dnok().
Sysadmins can fix it by putting no-check-names into /etc/resolv.conf.

---Dan