AAAA is a domain record, which is essentially the IPv6 address of the web server in which the domain is hosted. The IPv6 system was introduced to replace the present IPv4 system where each Internet protocol address comprises of 4 groups of decimal numbers ranging from 1 to 255 e.g. 18.104.22.168. However, an IPv6 address features eight groups of four hexadecimal digits - from 0 to 9 and from A to F. The reason for this transformation is the substantially smaller selection of unique IPs the existing system supports as well as the rapid increase of devices which are connected to the world wide web. An illustration of an IPv6 address would be 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you need to forward a domain address to a server which uses this kind of an address, you'll have to create an AAAA record for it, not the widespread A record, which is an IPv4 address. Both records provide the same exact function, but different notations are used, to differentiate the two types of addresses.