Each device that is connected to the world wide web has a unique identifier called IP (Internet Protocol) address. This includes computer systems, web servers, smart phones, switches, etc. The pool of IP addresses, which was introduced originally, has already been distributed, so 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, which is the address of the server where it's hosted. Using the IPv4 system, the record is called A and it comprises of four sets of numbers from 1 to 255 separated by a dot, while within the IPv6 system it's called AAAA and it is comprised of eight sets of hexadecimal numbers i.e. this type of records use digits 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 works with a substantially bigger number of IPs than the IPv4 format.