Every single device which is connected to the web has a special identifier known as IP (Internet Protocol) address. This includes PCs, web servers, smart phones, switches, etc. The pool of IP addresses, which was introduced at first, has already been distributed, therefore the so-called IPv4 IP addresses are gradually getting replaced with IPv6 addresses. Every domain which opens a site comes with an IP record, which is the address of the server where it's hosted. With the IPv4 system, the record is called A and it comprises of 4 sets of numbers from 1 to 255 separated with a dot, while in the IPv6 system it is called AAAA and it is comprised of 8 groups of hexadecimal numbers i.e. this sort of records use digits from 0 to 9 and letters from A to F. An example of an AAAA record is 2010:0c48:43d3:2142:1012:8c3a:2475:2435 and this format works with a substantially bigger amount of IPs than the IPv4 format.