An A Record Returns a 32-bit IPv4 address, most commonly used to map hostnames to an IP address of the host, but also used for DNSBLs, storing subnet masks in RFC 1101, etc.
A mail exchanger record (MX record) is a type of resource record in the Domain Name System that specifies a mail server responsible for accepting email messages on behalf of a recipient's domain
A CNAME Record is an alias of one name to another: the DNS lookup will continue by retrying the lookup with the new name. A CNAME record is an abbreviation for Canonical Name record and is a type of resource record in the Domain Name System (DNS) that specifies that the domain name is an alias of another, canonical domain name. Here "canonical" usually means: a more generally accepted or standard name. This helps when running multiple services (like an FTP server and a webserver; each running on different ports) from a single IP address. Each service can then have its own entry in the DNS (like ftp.example.com andwww.example.com).