AAAA is a domain 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 existing IPv4 system where each IP comprises of 4 sets of decimal numbers ranging from 1 to 255 e.g. 18.104.22.168. On the other hand, an IPv6 address has 8 sets of four hexadecimal digits - which range from 0 to 9 and from A to F. The main reason for this change is the substantially smaller amount of unique IPs the current system supports and also the speedy increase of units which are connected to the Internet. An illustration of an IPv6 address would be 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you want to forward a domain name to a web server which uses this sort of an address, you will have to set up an AAAA record for it, not the commonly used A record, that is an IPv4 address. The 2 records have the very same function, yet different notations are used, so as to distinguish the two types of addresses.