AAAA is a domain address record, that's 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 where every single IP consists of four groups of decimal numbers which range from 1 to 255 e.g. 220.127.116.11. However, an IPv6 address has eight groups of four hexadecimal digits - ranging from 0 to 9 and from A to F. The cause of this transformation is the tremendously smaller amount of unique IPs that the current system supports as well as the quick increase of units that are connected to the world wide web. An illustration of an IPv6 address is 2101:1f34:32e2:2415:1365:4f2b:2553:1345. If you'd like to point a domain to a server that uses such an address, you need to set up an AAAA record for it, and not the commonly used A record, that is an IPv4 address. The two records have the very same function, yet different notations are used, so as to differentiate the two types of addresses.