Each device which is connected to the web has a distinctive identifier called IP (Internet Protocol) address. This includes PCs, web servers, smartphones, switches, etc. The pool of addresses, which was introduced originally, has been distributed, therefore the so-called IPv4 IP addresses are slowly getting replaced with IPv6 addresses. Every domain which opens a website has an IP record, that is the address of the server where it's hosted. Using the IPv4 system, the record is called A and it is comprised of 4 sets of numbers from 1 to 255 divided with a dot, while in the IPv6 system it's called AAAA and it is made up of 8 sets 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 greater number of IPs compared with the IPv4 format.