AAAA is a domain name record, which is basically the IPv6 address of the server where the domain name is hosted. The IPv6 system was designed to replace the current IPv4 system in which each IP is comprised of four groups of decimal digits ranging from 1 to 255 e.g. 5.168.208.143. In comparison, an IPv6 address has 8 groups of four hexadecimal numbers - ranging from 0 to 9 and from A to F. The cause of this change is the tremendously smaller number of unique IPs the existing system supports as well as the rapid increase of units which are connected to the world wide web. An example of an IPv6 address would be 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you want to direct a domain to a server that uses such an address, you have to set up an AAAA record for it, and not the widespread A record, that is an IPv4 address. Both records have the same exact function, yet different notations are used, in order to identify the two forms of addresses.