In message <[email protected]>, Yonghua Peng writes: > > > mail.china.com. IN MX 10 mx-mail-china-com.icoremail.net. > > > Even if they have setup this, but the DNS clients never have the chance > to get the correct MX but always get a CNAME answer. Am I right?
It would be a alternative to a CNAME. You you are publishing email addresses as user@domain then there really should be a MX record at domain. There really doesn't need to be a double level of indirection. Today you get: ;; ANSWER SECTION: mail.china.com. 500 IN CNAME mail.china.com.cachecn.com. mail.china.com.cachecn.com. 201 IN MX 10 mx-mail-china-com.icoremail.net. A better cleaner setup would be: ;; ANSWER SECTION: mail.china.com. 500 IN 10 mx-mail-china-com.icoremail.net. I suspect that almost all of the presure to change the CNAME behaviour for MX records came about because people abused CNAME for HTTP. It has never been hard to add new record types to the DNS. People just thought it was hard so they never started the process. As a result SMTP behaviour was changed rather than the simple thing of adding a record for HTTP to the DNS. You end up with stupid sets of records like these because people wern't willing to do the little bit of effort to actually get a clean setup. > $ dig mail.china.com mx @ns-bgp.china.com > > ; <<>> DiG 9.8.1-P1 <<>> mail.china.com mx @ns-bgp.china.com > ;; global options: +cmd > ;; Got answer: > ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23565 > ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 > ;; WARNING: recursion requested but not available > > ;; QUESTION SECTION: > ;mail.china.com. IN MX > > ;; ANSWER SECTION: > mail.china.com. 500 IN CNAME mail.china.com.cachecn.com. > > ;; Query time: 75 msec > ;; SERVER: 124.248.35.12#53(124.248.35.12) > ;; WHEN: Mon Aug 11 09:24:44 2014 > ;; MSG SIZE rcvd: 69 > > > As you see, I queried for MX but got a CNAME. Thanks. -- 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
