IPv4 is the fourth version of the IP (Internet Protocol), and the first to be widely used around the world. IPv6 is the protocol that will replace IPv4 and is not yet in widespread use. By the end of 2012, only 1% of Internet traffic was using IPv6.
IPv4 uses 32-bit addresses; the maximum number of addresses is 4294967296. IPv6 offers a larger number of addresses than the fourth version, as it uses 128-bit addresses. IPv4 addresses will run out in a few years, that’s why IPv6 was created. These addresses are most often written in their dotted decimal form, but there are other ways of writing them.
- Dotted decimal form: 91.227.139.38
- Decimal form: 1541638950
- Hexadecimal form: 5be38b26
- Octal form: 13370705446
Structure of IPv4
IP addresses are allocated by regional Internet Registries, there are Registries in Africa, North America, South America, Asia and Europe. Each registry uses a WHOIS database where anyone can find the relevant data for any IP address. You can find the database of the European registry. On their website, type the IP address into the search bar.
Of the 4 billion potential IPv4 addresses, three blocks are reserved for private networks. These IP addresses cannot connect to public networks, this is only possible with network address translation. The three reserved blocks are in the following areas:
10.0.0.0-10.255.255.255 approx. 16 million addresses 172.16.0.0-172.31.255.255 approx. 1 million addresses 192.168.0.0-192.168.255.255 approx. 65.000 addresses.
IP allows different networks to communicate with each other, regardless of their physical size. The networks, which have different hardware, usually differ in their data transmission speed and in the maximum size of data packets that can be sent through them (Maximum Transmission Unit). When a network wants to send data to a network with a smaller MTU, IP breaks the data into smaller packets that the smaller network can receive. In IPv4, this function is part of the Internet layer and is performed by an IPv4 router. In contrast, IPv6 doesn’t allow for the routers to separate the data packets, the hosts have to design a packet size that can be received by the receiving address.