AAAA is a domain name record, that is in essence the IPv6 address of the server where the domain is hosted. The IPv6 system was introduced to replace the existing IPv4 system where each Internet protocol address consists of 4 sets of decimal digits between 1 to 255 e.g. 18.104.22.168. In contrast, an IPv6 address has 8 groups of four hexadecimal numbers - which range from 0 to 9 and from A to F. The reason for this transformation is the significantly smaller number of unique IPs the present system supports as well as the speedy increase of devices which are connected to the Internet. An illustration of an IPv6 address would be 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you'd like to direct a domain address to a web server which uses such an address, you will need to set up an AAAA record for it, and not the widespread A record, which is an IPv4 address. The two records provide the same exact function, yet different notations are used, to differentiate the two types of addresses.