Underscores in host names

Thu May 19 16:09:20 UTC 2005

At 8:52 -0700 5/19/05, Roger Marquis wrote:
>On Thu, 19 May 2005 Valdis.Kletnieks at vt.edu wrote:
...
>>  Don't like RFC3490 and its xn-- hostnames? ;)

xn--... aren't host names, they are domain names.  The host name 
corresponding to that would be something my simple minded mail 
application can't accept as input.

>Most definitely not, and if this were 1985 I'd be {rf}commenting on
>the inadvisability of such hostnames, and those beginning or ending
>with "-", TLD names shorter than 2 or longer than 4 characters,
>spaces in hostnames, [^a-z0-9\\-\\.], and other such marginally
>useful but infinitely problematic features.
>
>There is real value in KIS, and not just from the perspective of a
>security-minded coder...

KIS is great, if it gets the job done.  Systems that are too simple 
are useless too.

Supporting "IDN" is a necessary job.  That's been made clear to the 
Internet community.  If it "complicates" things, well, then that's 
what has to be done.  If the Internet is to be global, it can't 
restrict the world to just a few convenient languages.

It's true that the xn-- convention isn't the best way to encode 
IDN's, but it has proven to be the optimal one in design (at least). 
It would have been nice to use a new domain name label type, but 
we've about run out of them.  It would have been nice to use domain 
classes and use this to create a new domain name syntax, but that 
can't be done either.  Encoding IDNs this way ("xn--") is optimal 
according to the considered opinion of the IETF, at least those 
working on RFC 3490 (published in 2003), when you consider impacts on 
other protocols and applications.

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Edward Lewis                                                +1-571-434-5468
NeuStar

If you knew what I was thinking, you'd understand what I was saying.