Look up the IPv4 address a hostname resolves to, read straight from authoritative DNS rather than a cache.
An A record points at a web server. None of the records that decide whether your email is trusted live here.
It maps a hostname like www.example.com to an IPv4 address so browsers know which server to reach.
An A record points to an IP address. A CNAME points to another hostname, which is then resolved to an IP.