Every device that is connected to the web has a specific identifier called IP (Internet Protocol) address. This includes PCs, web servers, smart phones, switches, etcetera. The pool of IP addresses, which was introduced originally, has already been distributed, hence the so-called IPv4 IP addresses are steadily being replaced with IPv6 addresses. Every domain which opens an internet site comes with an IP record, which is the address of the server where it's hosted. When using the IPv4 system, the record is called A and it is comprised of four groups of numbers from 1 to 255 divided with a dot, while within 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. An example of an AAAA record is 2010:0c48:43d3:2142:1012:8c3a:2475:2435 and this format supports a considerably larger amount of IPs than the IPv4 format.