Re: Update of RFC 2606 based on the recent ICANN changes ?

Lyman Chapin <> Mon, 07 July 2008 15:45 UTC

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From: Lyman Chapin <>
Subject: Re: Update of RFC 2606 based on the recent ICANN changes ?
Date: Thu, 3 Jul 2008 16:59:50 -0400
To: Bernard Aboba <>
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I understand the objection to MX records in TLDs based on the past  
history of how single label hostnames were (and, as Mark points out,  
undoubtedly still are) handled. If it were possible to put that  
aside, would you have any other objection to single label hostnames?  
I know that at least some of the interest in new gTLDs has been  
expressed by companies that like the idea of using a globally- 
recognized trademark as a TLD - for example,  
"customerservice@ibm" (not to imply that IBM is one of the companies  
that has expressed this sort of interest).

I'm familiar with <draft-klensin-rfc2821bis-10.txt> and understand  
the importance of using only FQDNs in SMTP exchanges given that "[i]n  
the case of a top-level domain used by itself in an email address, a  
single string is used without any dots." What I'm interested in is  
any reason to proscribe the use of a TLD as a single label hostname  
(particularly for email addresses) other than the fact that there is  
software out there that will interpret it incorrectly -

- Lyman

On Jul 2, 2008, at 8:07 PM, Bernard Aboba wrote:
> Mark Andrews said:
> "The Internet went to multi-label hostnames ~20 years ago.We added  
> ".ARPA" to all the single label hostnames as partof that process.  
> The only hold over is "localhost" andthat is implemeted locally,  
> not in the global DNS. No sane TLD operator can expect "http://tld"  
> or "user@tld"to work reliably. I suspect there are still mail  
> configuationsaround that will re-write "user@tld" to  
> user@tld.ARPA.Should we be writting a RFC which states that MX and  
> addressrecords SHOULD NOT be added to the apex of a TLD zone?
> Should we be writting a RFC which states that single labelhostnames/ 
> mail domains SHOULD NOT be looked up "as is" inthe DNS?"
> Both sound like good ideas to me.
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