[dns-operations] MX CNAMEs

[Jason Sherron]

CloudFlare's take on the related CNAME issue with an explicit calling-out of MS Exchange for MX records

http://blog.cloudflare.com/introducing-cname-flattening-rfc-compliant-cnames-at-a-domains-root/

(Yes, I work for MSFT but have no opinion or knowledge of the specifics here. I just liked the article.)


-----Original Message-----
From: dns-operations [mailto:dns-operations-bounces at dns-oarc.net] On Behalf Of Mark Andrews
Sent: Thursday, December 25, 2014 11:39 PM
To: 风河
Cc: dns-operations at dns-oarc.net
Subject: Re: [dns-operations] MX CNAMEs

Just because it works some of the time that doesn't mean that it will work all of the time. The cname rule is there to cope with multiple mx records with different preferences.  It also comes into play when there is a misconfiguration with a single mx.
 
The visible effect is that you get a mail loop rather than queuing of the email or a bounce. 

On 26/12/2014, at 17:17, 风河 <news at windwrite.com> wrote:

> I was thinking MX should not be a CNAME record.
> But these two are broken the rules, and they seem work just fine?
> 
> 2008.sina.com.        52    IN    MX    10 mx.2008.sina.com.
> 
> mx.2008.sina.com.    8    IN    CNAME    freemx1.sinamail.sina.com.cn.
> freemx1.sinamail.sina.com.cn. 8    IN    A    202.108.3.242
> 
> And,
> 
> mail.china.com.        391    IN    CNAME    mail.china.com.cachecn.com.
> mail.china.com.cachecn.com. 191    IN    MX    10 mx-mail-china-com.icoremail.net.
> 
> Thanks.
> _______________________________________________
> dns-operations mailing list
> dns-operations at lists.dns-oarc.net
> https://lists.dns-oarc.net/mailman/listinfo/dns-operations
> dns-jobs mailing list
> https://lists.dns-oarc.net/mailman/listinfo/dns-jobs

_______________________________________________
dns-operations mailing list
dns-operations at lists.dns-oarc.net
https://lists.dns-oarc.net/mailman/listinfo/dns-operations
dns-jobs mailing list
https://lists.dns-oarc.net/mailman/listinfo/dns-jobs