Every single device that's connected to the Internet has a unique identifier referred to 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 been distributed, hence the so-called IPv4 IP addresses are steadily being replaced with IPv6 addresses. Every domain name that opens an internet site has 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 comprises of four groups of numbers from 1 to 255 separated by a dot, while within the IPv6 system it is called AAAA and it is made up of eight sets of hexadecimal numbers i.e. this kind of records use numbers from 0 to 9 and letters from A to F. An illustration of an AAAA record is 2010:0c48:43d3:2142:1012:8c3a:2475:2435 and this format works with a substantially larger number of IPs than the IPv4 format.