DNS question, null MX records

Mark Scholten mark at streamservice.nl
Tue Dec 15 15:31:08 UTC 2009


Hello,

You could use:
Local.example.com.	IN	A	127.0.0.1
Example.com.	IN	MX	10	local.example.com.

This way systems shouldn't deliver it at your system.

What you did mention is something we don't allow our customers to do (if I
am correct).

With kind regards,

Mark Scholten

-----Original Message-----
From: Eric J Esslinger [mailto:eesslinger at fpu-tn.com] 
Sent: dinsdag 15 december 2009 16:18
To: 'nanog at nanog.org'
Subject: DNS question, null MX records

I have a domain that exists solely to cname A records to another domain's
websites. There is no MX server for that domain, there is no valid mail sent
as from that domain. However when I hooked it up I immediately started
getting bounces and spam traffic attemtping to connect to the cnamed A
record, which has no inbound mail server (It's actually hitting the firewall
in front of it). (The domain name is actually several years old and has been
sitting without dns for a while)

I found a reference to a null MX proposal, constructed so:
example.com    IN    MX 0 .

Question: Is this a valid dns construct or did the proposal die? I don't
want to cause people problems but at the same time, I don't want any of this
crap to even attempt to deliver on this domain to any of my servers.


__________________________
Eric Esslinger
Information Services Manager - Fayetteville Public Utilities
http://www.fpu-tn.com/
(931)433-1522 ext 165



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