AAAA is a domain record, that's in essence the IPv6 address of the server in which the domain is hosted. The IPv6 system was designed to replace the current IPv4 system where every single Internet protocol address is comprised of four groups of decimal digits between 1 to 255 e.g. 126.96.36.199. In comparison, an IPv6 address includes 8 groups of four hexadecimal numbers - from 0 to 9 and from A to F. The main reason for this modification is the considerably smaller amount of unique IPs the present system supports as well as the fast increase of products that are connected to the world wide web. An example of an IPv6 address would be 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you need to direct a domain address to a machine that uses such an address, you will need to set up an AAAA record for it, and not the widespread A record, which is an IPv4 address. Both records have the exact same function, but different notations are used, in order to distinguish the two forms of addresses.