Confusion over MX Records

Question

I am very confused about the basics of DNS records (in this case MX records). I have registered a domain name now (call example.com). This domain is configured on my linode IP through their name servers.

By default, the MX record in the domain manager is "mail.example.com". Fair.

I followed this tutorial on setting up an Exim server.

Exim Tutorial at Linode Library

and I'm a little confused. My default name on the machine is "antare", and thus the fully qualified domain name is "antares.example.com". In this tutorial, I don’t see how this "mail.example.com" comes into play? Where can I point this out? Or should I point the MX mail account to antares.example.com?

I am very new to DNS records and even more new mail records. Any hints of clarification of my misunderstanding would be invaluable.

Answer 1

The DNS server for your domain will by default serve the www or .domain.com record for web browsers, etc., but in fact it contains a bunch of name pointers for other services, one of which is mail exchange.

Services that need your mx record value know how to look for it from your DNS server, so in this case they will find mail.domain.com when you provide the domain.com part.

If you need to configure the mail server, you will need to change the mx record in your domain manager to indicate your device IP address, this may differ from your default name / IP address www in the same domain as each service can Served by another host (any ip).