What should I specify in the DNS selector for a DKIM record?

Question

Domain Name System

Can you explain to me how to write a selector in my case
I have records

A example.com 127.0.0.1
MX example.com

that is, my mail server is located on the example.com domain
. I want to sign emails with DKIM with generated keys, etc.
It remains only to add an entry to the DNS, but then I ran into a misunderstanding.

Everyone writes that there should be a selector in the record

mail._domainkey.example.com. TXT "k=rsa\; t=s\; p=MI...QAB"

In this case, the mail selector. and mx record for this example mail.example.com
But as I understand it, there can be no empty selector, so what should I write in the selector if I have 1 server on the example.com domain?

Answer 1

A DKIM record has nothing to do with other DNS records. This is just a pair of keys, you publish the mail._domainkey records in the DNS with the public one, and sign all outgoing letters on the mail server with the private one.
Leave mail._domainkey.example.com as the default.