Every device that's connected to the web has a specific identifier referred to as IP (Internet Protocol) address. This includes computer systems, web servers, smart phones, switches, etc. The pool of IP addresses, that was introduced initially, has already been distributed, hence the so-called IPv4 IP addresses are gradually being replaced with IPv6 addresses. Every domain which opens an internet site comes with 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 four groups of numbers from 1 to 255 separated using a dot, while with 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. A good example of an AAAA record is 2010:0c48:43d3:2142:1012:8c3a:2475:2435 and this format supports a considerably larger number of IPs in comparison with the IPv4 format.