What are IPv4 addresses?
First, some background. Every computer or mobile device that can talk to the Internet needs a globally unique address. This allows the device to send network data out to a remote host (say, www.infoq.com) and get the right data back. To make things easier for humans, the Domain Name Service (DNS) translates familiar names into such IPv4 addresses. For example, when you browse to this website, DNS translates it to the globally unique 63.246.7.184; and whenever your browser sends a request, it leaves a ‘return to’ address like 216.239.59.99. These four numerals are known as the IPv4 address, or sometimes just IP address. Given that each one can be between 0 and 255, there’s about 4.3 billion possible IP addresses. Clearly, there’s an upper limit to the number of devices – and in comparison, there’s 6.7 billion people on the planet. Even in an ideally distributed world, that still means that there’s on average one IP address for two people; and yet, in the West, there are many devices whi
