An A record is a record that indicates the correspondence between a domain name and an IP address. In a second-level domain, domain.com usually create an A record of the form www, mail, ftp, and so on, which ensure the operation of names like www.domain.com, mail.domain.com, ftp.domain.com.
A CNAME (canonical name) record is an alias record for a domain, for example, you can create a CNAME of the form name.domain.com an alias for a domain www.domain.com
An MX (mail exchanger) record makes mail routing work. It indicates to the