A (Address) records are IPv4 addresses. They can be added to point a domain name to a different hosting company, or different subdomains of a site to external services.
AAAA records are IPv6 addresses. Similar to A records, they are used to point a domain or subdomain to a hosting service. AAAA records are less common than A records, since most internet traffic runs over IPv4.
ALIAS records are virtual DNS records, similar to CNAME, but ALIAS records may be added to the root domain name (which is not possible with a CNAME). ALIAS records may be added to a subdomain record that already exists, whereas each CNAME must be unique. Since an ALIAS record query returns an IP address, it can be used anywhere an A record can be used.
CNAME (Canonical Name) records are used to point a subdomain to another hostname, as opposed to an IP address with a custom A record. A CNAME is often used to point the “www” subdomain to the root domain (example.com) so that visitors may reach the site at either address. CNAME records cannot be applied to the root domain. Instead, use an ALIAS record.
MX (Mail Exchange) records are required to receive email. They tell the world which mail servers accept incoming mail for a domain, and where emails sent to that domain should be routed to. When multiple MX records are specified for a domain, the priority value controls which MX record is used first.
TXT (Text) records are free-form strings that allow an administrator to associate text with a domain or subdomain. TXT records are commonly used for Google site verification, or for adding SPF, DMARC, and DKIM signing for mail services.
