Every device which is connected to the web has a unique identifier called IP (Internet Protocol) address. This includes PCs, web servers, smart phones, switches, and so on. The pool of addresses, that was introduced at first, is already distributed, hence the so-called IPv4 IP addresses are progressively being replaced with IPv6 addresses. Every domain name that opens a site comes with an IP record, that is the address of the server where it's hosted. With the IPv4 system, the record is called A and it is comprised of 4 groups of numbers from 1 to 255 separated using a dot, while within the IPv6 system it's called AAAA and it comprises of 8 groups of hexadecimal numbers i.e. this sort 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 bigger number of IPs than the IPv4 format.