[dns-operations] Curious use of cname

Dave Warren davew at hireahit.com
Sun Aug 10 08:56:10 UTC 2014

On 2014-08-09 21:06, Yonghua Peng wrote:
> Hi,
> @mail.china.com does provide free email service, and they have a large 
> number of user base.
> And their MX setup:
> mail.china.com. 297 IN CNAME mail.china.com.cachecn.com.
> mail.china.com.cachecn.com. 97 IN MX 10 mx-mail-china-com.icoremail.net.
> Will some email deliver systems break due to this setup? Thanks.

Is "mail.china.com" used as the target of a MX record anywhere? If so, 
then yes, you'll see breakage.

Outside of that, you might find an ancient mail server that will rewrite 
@mail.china.com addresses to @mail.china.com.cachecn.com but otherwise I 
wouldn't expect anything to explode.

Dave Warren

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