AAAA is a domain record, that is essentially the IPv6 address of the server where the domain is hosted. The IPv6 system was designed to replace the current IPv4 system where every IP consists of four groups of decimal numbers ranging from 1 to 255 e.g. 18.104.22.168. In comparison, an IPv6 address has eight sets of four hexadecimal numbers - which range from 0 to 9 and from A to F. The reason behind this transformation is the substantially smaller number of unique IPs that the existing system supports and also the fast increase of devices which are connected to the world wide web. An illustration of an IPv6 address would be 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you'd like to point a domain address to a web server that uses this kind of an address, you will have to create an AAAA record for it, not the widespread A record, that is an IPv4 address. The 2 records have the very same function, but different notations are used, in order to differentiate the two types of addresses.