AAAA is a domain record, that is essentially the IPv6 address of the server in which the domain name is hosted. The IPv6 system was intended to replace the present IPv4 system where every single IP consists of four groups of decimal digits ranging from 1 to 255 e.g. 5.168.208.143. However, an IPv6 address includes 8 groups of four hexadecimal numbers - which range from 0 to 9 and from A to F. The cause of this transformation is the considerably smaller amount of unique IPs which the current system supports and the quick increase of devices that are connected to the Internet. An illustration of an IPv6 address is 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you'd like to forward a domain name to a web server which uses such an address, you'll have to set up an AAAA record for it, not the commonly used A record, which is an IPv4 address. Both records deliver the same exact function, yet different notations are used, to separate the two forms of addresses.