[dns-operations] MX CNAMEs
marka at isc.org
Sat Dec 27 01:53:11 UTC 2014
In message <45fb5af36ca944258e05c493da5a7fcb at DFM-DB3MBX15-07.exchange.corp.microsoft.com>, Jason
> CloudFlare's take on the related CNAME issue with an explicit calling-out
> of MS Exchange for MX records
> (Yes, I work for MSFT but have no opinion or knowledge of the specifics
> here. I just liked the article.)
Which is unrelated to the use CNAME of as MX/SRV targets.
> -----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
> 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, <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 18.104.22.168
> > And,
> > mail.china.com. 391 IN CNAME mail.china.com.cachecn.com.
> > mail.china.com.cachecn.com. 191 IN MX 10
> > 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
> dns-jobs mailing list
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka at isc.org
More information about the dns-operations