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Re: Services and top-level DNS names (was: Re: Update of RFC 2606)

2008-07-07 09:51:57

In an earlier message,  John C Klensin <john-ietf(_at_)jck(_dot_)com> wrote:

Part of the problem in that case was that, because JANET used
little-endian names internally, the big-endian foo.ucl.ac.uk (in
DNS order) had to be be mapped into uk.ac.uck.foo (in JANET
order) and vice versa.  That mapping was trivial as long as one
could run a simplistic "whichever end the TLD was on had to be
the big side" test.  When "CS" was introduced, blew up that
simple test.  In the JANET case, it failed since there were
strings that could be TLDs at both ends of the string, i.e., in
principle, cs.ucl.ac.uk could have been a string that was
already in JANET order and that would appear in the DNS order as
uk.ac.ucl.cs.

I tried getting Peter Kirstein to comment on this, but he's unfortunately currently away, so I'll voice my own opinions here and please bear with me because Peter's knowledge far exceeds mine. After all, I was only a terrible teenager at the time.

IMHO you cannot compare today's challenges with the way things were handled in 1989 or so...

JANET was using NRS, not DNS. NRS was a static mapping of UK computer addresses in NRS format, ie. UK.AC.SOMEPLACE.SOMECOMPUTER to X.3 PAD numbers accessed over X.25. NRS pre-dated the DNS. Getting e-mail in and out of the UK made use of several gateways that on the UK side we need to know, and on the other end of the line people either needed to know, or you'd send to a gateway that would know.

There were several gateways in the UK:

EARN RELAY - located at Rutherford Appleton Labs as a path to BITNET (UKACRL node)
EAN RELAY - to X.400 & other European Networks
UK.AC.UCL.CS.NSS - the precursor to nsfnet-relay.ac.uk - satellite link to the Internet
UK.AC.UKC - University of Kent at Canterbury's UUCP service

Back in those days, you could route your email specifically - something which very few mailers allow today.
For example, I could send email to an Internet address 
foo(_at_)foo(_dot_)bar(_dot_)com as:
To: foo%com(_dot_)bar(_dot_)foo(_at_)uk(_dot_)ac(_dot_)ucl(_dot_)cs(_dot_)nss

or

to: foo%foo(_dot_)bar(_dot_)com%CUNYVM(_at_)uk(_dot_)ac(_dot_)earn-relay (this one crossing the pond via BITNET & bridging to the Internet via cuny)

Note that the NSS Relay used to reverse the addressing automatically. In the early days, it used to try and check which way the addressing was. Then came CS and you are correct in saying that it caused problems. But the problems were not nearly as serious as you say. Rules were changed that you simply needed to write the address in the correct order for your email to be delivered.

For those that have a historical interest (and would perhaps like to get inspired technically to resolve possible future problems with gTLDs), I suggest you read the excellent document written by Tim Clark of Warwick University back in those days. It used to be my email bible for quite a while and a few copies still float around the net. You can find a dusty copy here: http://iubio.bio.indiana.edu/soft/help/old/email-gateways.txt

Last but not least, IMHO the issue of mit(_at_)ai is a non issue. I think we need to come to terms that the age of a resolver trying out every known local domain/sub-domain is dying out. From now on, you'll need to provide an exact host/domain name. It is not the first and not the last habit to die on the Internet. Take bang! paths, for example: dead. hostname.uucp - dead. And I also think that what web browsers try to do by suggesting a page when you just type "somefooplace" -> opens somefooplace.com is also a "feature" that will need to die to ensure stability. There are simply too many "somefooplace" on the internet, and now "somefooplace" might even be .somefooplace Or ISPs might even resolve locally "somefooplace" to "somefoobarplace" - clearly there is no limit to foo.

Warm regards,

Olivier

--
Olivier MJ Crepin-Leblond, Ph.D.
E-mail:<ocl(_at_)gih(_dot_)com> | http://www.gih.com/ocl.html
http://www.nsrc.org/codes/country-codes.html

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