AAAA is a domain name record, that's in essence the IPv6 address of the web server in which the domain is hosted. The IPv6 system was designed to replace the present IPv4 system where every IP address is comprised of 4 groups of decimal numbers ranging from 1 to 255 e.g. 5.168.208.143. In contrast, an IPv6 address has eight sets of four hexadecimal digits - which range from 0 to 9 and from A to F. The cause of this transformation is the significantly smaller amount of unique IPs the existing system supports and the quick increase of units that are connected to the Internet. An example of an IPv6 address would be 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you wish to point a domain address to a web server which uses such an address, you will have to set up an AAAA record for it, not the commonly used A record, which is an IPv4 address. Both records have the same exact function, yet different notations are used, to distinguish the two forms of addresses.