Reverse DNS Resolve for MX record

Bruno Vieira asked:

I’ve two servers running, one is a webserver and it’s A record on my (external) DNS provider is in the form of:

example.com in A XXX.XX.XXX.171

The other is a mailserver and it’s A record is in the form:

mail.example.com in A XXX.XX.XXX.170

and it’s mx record is in the form:

example.com in MX 10 mail.example.com

How should my DNS reverse (i.e. my ISP provider) resolve:

example.com or mail.example.com?

BTW, this is how my /etc/hosts file looks like:

127.0.0.1   mail.example.com mail example.com
::1     mail.example.com mail example.com

Thanks in advance for all the help

My answer:


Have both of them matched exactly. i.e.

171 IN PTR example.com.
170 IN PTR mail.example.com.

In fact you can just copy and paste that to your ISP; that’s exactly how it will look in their bind (DNS server) configuration.


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