In message <45fb5af36ca944258e05c493da5a7...@dfm-db3mbx15-07.exchange.corp.microsoft.com>, Jason Sherron writes: > 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-cnam > es-at-a-domains-root/ > > (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:[email protected] On Behalf > Of Mark Andrews > Sent: Thursday, December 25, 2014 11:39 PM > To: > 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, <[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 -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: [email protected] _______________________________________________ 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
