AAAA is a domain name record, that is essentially the IPv6 address of the web server where the domain name is hosted. The IPv6 system was introduced to replace the present IPv4 system where each IP address is comprised of 4 groups of decimal numbers which range from 1 to 255 e.g. 18.104.22.168. On the other hand, an IPv6 address has eight sets of 4 hexadecimal digits - ranging from 0 to 9 and from A to F. The reason for this modification is the substantially smaller selection of unique IPs that the existing system supports as well as the fast increase of units which are connected to the world wide web. A good example of an IPv6 address would be 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you wish to forward a domain to a web server which uses such an address, you have to set up an AAAA record for it, not the commonly used A record, which is an IPv4 address. The 2 records have the exact same function, but different notations are used, to separate the two sorts of addresses.