Re: i18n of DNS (was: Re: UTF-5 ?

From: John Cowan (
Date: Fri Oct 29 1999 - 11:04:19 EDT

"Martin J. Duerst" wrote:

> I invented UTF-5 roughly three years ago to show that it is possible
> to use the DNS with its current restrictions on host names to store
> internationalized domain names.

Actually, the DNS has no notion of host names, but only domains. The
assumption that certain domains have host names at the end is purely
conventional. The real culprit is RFC 952, which dates back to 1985
and describes the format of the (obsolescent) /etc/hosts file.
The relevant section reads as follows:

# 1. A "name" (Net, Host, Gateway, or Domain name) is a text string up
# to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus
# sign (-), and period (.). Note that periods are only allowed when
# they serve to delimit components of "domain style names". (See
# RFC-921, "Domain Name System Implementation Schedule", for
# background). No blank or space characters are permitted as part of a
# name. No distinction is made between upper and lower case. [The first
# character must be an alpha character.] The last character must not be
# a minus sign or period. A host which serves as a GATEWAY should have
# "-GATEWAY" or "-GW" as part of its name. Hosts which do not serve as
# Internet gateways should not use "-GATEWAY" and "-GW" as part of
# their names. A host which is a TAC should have "-TAC" as the last
# part of its host name, if it is a DoD host. Single character names
# or nicknames are not allowed.

The sentence in brackets was voided by RFC 1123, which allows either alphas
or digits at the beginning of names.

IMHO it is simply time to override this 15-year-old standard and allow
arbitrary non-ASCII characters, coded in standard UTF-8, as part of
hostnames. Of course, hosts that need to be accessible internationally
SHOULD still be given ASCII names as a matter of interoperability.
Latin case-blindness and the prohibition on all characters but "-" can
be kept for backward compatibility.


John Cowan Schlingt dreifach einen Kreis vom dies / Schliess eurer Aug vor heiliger Schau Den er genoss vom Honig-Tau / Und trank die Milch vom Paradies. -- Coleridge (tr. Politzer)

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