AAAA is a domain record, which is in essence the IPv6 address of the server in which the domain name is hosted. The IPv6 system was designed to replace the existing IPv4 system in which every single IP address comprises of 4 sets of decimal digits between 1 to 255 e.g. 18.104.22.168. However, an IPv6 address includes 8 groups of 4 hexadecimal digits - from 0 to 9 and from A to F. The reason behind this change is the substantially smaller amount of unique IPs the current system supports as well as the quick increase of units which are connected to the world wide web. An illustration of an IPv6 address is 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you want to forward a domain to a machine which uses this kind of an address, you have to create an AAAA record for it, and not the commonly used A record, which is an IPv4 address. Both records provide the very same function, but different notations are used, so as to distinguish the two forms of addresses.