how to use A-Record and mx-Record

I am not sure this is related to .net but i found this is as
The MX-record contains the host name of the computer(s) that handle the emails for a domain and a prioritization code. Emails are routed through to the IP address which is set in the A-record of the host.

The MX-record contains the host name of the computer(s) that handle the emails for a domain and a prioritization code. Emails are routed through to the IP address which is set in the A-record of the host.

The A-record (or address-record) determines which IP address belongs to a domain name. This record 'translates' the domain name to an IP address

Refer ---
http://www.copernica.com/en/about-us/news/a-record-and-mx-record-how-does-it-work

Hope this will help you

Thanks