AAAA is a domain record, that is in essence the IPv6 address of the server in which the domain is hosted. The IPv6 system was intended to replace the present IPv4 system in which every Internet protocol address consists of four groups of decimal numbers ranging from 1 to 255 e.g. 5.168.208.143. However, an IPv6 address has eight groups of 4 hexadecimal numbers - ranging from 0 to 9 and from A to F. The reason behind this modification is the tremendously smaller number of unique IPs the present system supports and also the fast increase of units which are connected to the Internet. A good example of an IPv6 address is 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you need to forward a domain to a web server which uses this type of an address, you will need to set up an AAAA record for it, not the commonly used A record, that is an IPv4 address. Both records have the same exact function, yet different notations are used, in order to distinguish the two forms of addresses.