Every single device which is connected to the web has a distinctive identifier called IP (Internet Protocol) address. This includes PCs, web servers, smartphones, switches, etcetera. The pool of IP addresses, that was introduced originally, has already been distributed, hence the so-called IPv4 IP addresses are slowly getting replaced with IPv6 addresses. Every domain which opens a site comes with an IP record, which is the address of the server where it is hosted. With the IPv4 system, the record is called A and it consists of four sets of numbers from 1 to 255 divided using a dot, while within the IPv6 system it's called AAAA and it consists of eight groups of hexadecimal numbers i.e. this kind of records use digits from 0 to 9 and letters from A to F. An example of an AAAA record is 2010:0c48:43d3:2142:1012:8c3a:2475:2435 and this format is designed for a substantially bigger number of IPs compared with the IPv4 format.