AAAA is a domain address record, that is basically the IPv6 address of the server where the domain name is hosted. The IPv6 system was intended to replace the existing IPv4 system in which every IP address consists of 4 sets of decimal digits between 1 to 255 e.g. 18.104.22.168. In contrast, an IPv6 address has eight sets of 4 hexadecimal digits - from 0 to 9 and from A to F. The main reason for this transformation is the substantially smaller amount of unique IPs that the current system supports as well as the rapid increase of units which are connected to the Internet. A good example of an IPv6 address is 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you want to forward a domain name to a machine which uses such an address, you will have to set up an AAAA record for it, and not the widely used A record, which is an IPv4 address. Both records provide the exact same function, but different notations are used, to differentiate the two sorts of addresses.