Every single device that is connected to the web has a unique identifier named IP (Internet Protocol) address. This includes computer systems, web servers, smart phones, switches, etc. The pool of IP addresses, that was introduced initially, is already distributed, so the so-called IPv4 IP addresses are slowly being replaced with IPv6 addresses. Every domain name which opens an internet site has 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 made up of four groups of numbers from 1 to 255 split up using a dot, while with the IPv6 system it is called AAAA and it is comprised of eight groups 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 can handle a significantly bigger number of IPs compared with the IPv4 format.