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 every single Internet protocol address consists of four groups of decimal numbers between 1 to 255 e.g. 18.104.22.168. However, an IPv6 address has eight groups of 4 hexadecimal numbers - ranging from 0 to 9 and from A to F. The main reason for this transformation is the significantly smaller range of unique IPs the existing system supports and also the quick 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'd like to point a domain to a machine which uses this type of an address, you'll have to set up an AAAA record for it, not the widely used A record, which is an IPv4 address. The two records provide the very same function, yet different notations are used, so as to separate the two forms of addresses.