On Jul 19, 2014, at 1:59 AM, Viktor Dukhovni
<ietf-dane(_at_)dukhovni(_dot_)org> wrote:
On Fri, Jul 18, 2014 at 10:46:53AM -0400, Ted Lemon wrote:
On Jul 18, 2014, at 10:44 AM, John Levine <johnl(_at_)taugh(_dot_)com> wrote:
Well, OK. What would be the proper MX for mail sent to
ted(_at_)www(_dot_)ietf(_dot_)org?
divertimento% dig mx ietf.org
Sorry, no, that would be "dig mx www.ietf.org":
$ dig +noall +ans -t mx www.ietf.org
www.ietf.org. IN CNAME www.ietf.org.cdn.cloudflare.net.
so no MX records there...
But there are address records.
www.ietf.org.cdn.cloudflare.net. 87 IN A 104.20.1.85
www.ietf.org.cdn.cloudflare.net. 87 IN A 104.20.0.85
www.ietf.org.cdn.cloudflare.net. 116 IN AAAA 2400:cb00:2048:1::6814:55
www.ietf.org.cdn.cloudflare.net. 116 IN AAAA 2400:cb00:2048:1::6814:155
http://tools.ietf.org/html/rfc5321#section-5
,--
If an empty list of MXs is returned,
the address is treated as if it was associated with an implicit MX
RR, with a preference of 0, pointing to that host.
'--
Which means there are 4 implied MX records causing likely 4 timeouts depending
on how port 25 is handled.
Since there is no support to require use of MX records, the remaining solution
(although not as clean) is to create negated MX record.
Regards,
Douglas Otis