coredns: CNAME and other data: cannot serve MX entry for domain

I recently faced the issue that I am unable to set the MX record for the domain xyz.ab, but was able to do it for a subdomain sub.xyz.ab

I tried to set the MX record in many different ways:

@ IN  SOA ns1.example.org example.example.org. (
      2017091601	    ; Serial
      28800           ; Refresh
      7200            ; Retry
      864000          ; Expire
      86400   )       ; Min TTl

; Nameserver Information

             IN NS       ns1.example.org.
             IN NS       ns2.example.org.

; MX

             IN MX 10    mail.example.org.

I also tried to set it like this:

example.org. IN MX 10 mail.example.org. @ IN MX 10 mail.example.org.

I think this may be caused by this check (I’m not sure, I just checked a few issues related to MX on here) #531

I’m using the ‘file’ plugin

About this issue

Original URL
State: closed
Created 7 years ago
Comments: 22 (11 by maintainers)

Most upvoted comments

Alright! Thanks for creating it in the first place 😃

Waffeldrache on Oct 23, 2017

Ok thank you! So I actually managed to return a static valid MX response without leaking the CNAME! It actually only required 5 lines of code to catch it.

You did good code! Easy to read

Waffeldrache on Oct 23, 2017

There is no actual dropping, it’s keeping track of seeing the CNAME, plugin/file/lookup.go#L155 looks like a good starting place.

miekg on Oct 23, 2017