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Re: [Asrg] overloading server names doesn't work, was who has the message

2010-02-09 10:51:38


On 2/9/2010 8:40 AM, John R Levine wrote:
mail.btinternet.com. 600 IN CNAME pop-smtp.bt.mail.yahoo.com.
pop-smtp.bt.mail.yahoo.com. 1800 IN CNAME
pop-smtp.bt.mail.fy5.b.yahoo.com.
pop-smtp.bt.mail.fy5.b.yahoo.com. 300 IN A 217.12.13.134
pop-smtp.bt.mail.fy5.b.yahoo.com. 300 IN A 217.146.188.192

I don't hack DNS records enought to be sure, but it appears to need
exactly one new record:

_report.pop-smtp.bt.mail.fy5.b.yahoo.com IN TXT 
abuse-report(_at_)yahoo(_dot_)com

Nope, that won't work. CNAMEs don't do a partial match.
Then I guess it's lucky I didn't specify one.

But you did. The CNAME only matches its exact name, and doesen't do a
partial match of names below it. RFC 2181 explains this, albeit not very
clearly.

Where did I or anyone else specify a partial match?


_report.pop-smtp.bt.mail.fy5.b.yahoo.com IN TXT 
abuse-report(_at_)yahoo(_dot_)com
_report.pop-smtp.bt.mail.yahoo.com IN TXT abuse-report(_at_)yahoo(_dot_)com
_report.mail.btinternet.com IN TXT abuse-report(_at_)yahoo(_dot_)com

That won't work, either. You can't have DNS records below a CNAME.

I'm not finding where that restriction specified among the list of
restrictions I can find, and apparently all of popular the summaries
written about CNames have missed it too.

Please cite the standards text that specifies it.

Also 2181. I'll go see if there's a clearer explanation somewhere else.

Normally, something finer-grained that a reference to all of 15 pages would be expected.

And here it is essential, because I still do not see its specifying what you are claiming.

Please cite the specific text that asserts the constraint that you believe makes it illegal to have a subdomain name, under a domain with a CNAME.


d/
--

  Dave Crocker
  Brandenburg InternetWorking
  bbiw.net
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