Each device which is connected to the Internet has a unique identifier referred to as IP (Internet Protocol) address. This includes PCs, web servers, smart phones, switches, and so on. The pool of IP addresses, which was introduced originally, is already distributed, hence the so-called IPv4 IP addresses are gradually being replaced with IPv6 addresses. Every domain that opens a website comes with an IP record, that is the address of the server where it is hosted. When using the IPv4 system, the record is called A and it consists of 4 sets of numbers from 1 to 255 separated using a dot, while in the IPv6 system it's called AAAA and it is made up of 8 groups of hexadecimal numbers i.e. this type of records use numbers from 0 to 9 and letters from A to F. A good example of an AAAA record is 2010:0c48:43d3:2142:1012:8c3a:2475:2435 and this format supports a significantly greater number of IPs when compared with the IPv4 format.