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:[email protected]] On Behalf Of Mark Andrews Sent: Thursday, December 25, 2014 11:39 PM To: 风河 Cc: [email protected] 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 <[email protected]> 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 > [email protected] > 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 [email protected] 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 [email protected] https://lists.dns-oarc.net/mailman/listinfo/dns-operations dns-jobs mailing list https://lists.dns-oarc.net/mailman/listinfo/dns-jobs
