You may have heard that IPv4 addresses are running out, but what are IPv4 addresses and how can they run out? Is there anything that can be done about it? To understand that, let's take a closer look at IP addresses in this article.

An IP address is a unique number that identifies a device on the Internet, similar to how a phone number is unique to a telephone. The IP in IP address stands for Internet Protocol. Its basis was developed as part of the TCP/IP model in the 1980s by the American DARPA (not to be confused with the World Wide Web developed by the European CERN).

For example, if you look up a domain name such as transip.nl in a browser, your computer will look in the so-called DNS records of transip.nl to see which IP addresses are linked to it. These IP addresses indicate where on the internet the server that hosts the associated transip.nl website is located.

IP addresses are issued worldwide by five registries and are actually always assigned to companies through them. For example, TransIP owns a large number of IP addresses that we assign to our services, such as a VPS or web hosting server. You get your IP address for your internet connection at home from your internet provider.

IPv4 vs IPv6 addresses

There are two versions of IP addresses in use: IPv4 addresses and IPv6 addresses (Internet Protocol version X). IPv4 and IPv6 addresses look like this, for example:

• IPv4 address: 192.168.2.2
• IPv6 address: 2a01:07c8:0000:0000:34f4:0000:0000:1337. In practice, a set of four zeros in an IPv6 address is usually abbreviated and looks like this: 2a01:7c8::34f4:0:0:1337.

IPv4 addresses consist of 32 bits and IPv6 addresses consist of 128 bits. A bit is the smallest unit of data on a computer, namely 1 or 0. This is also called binary code and equals power on or off, true or false. Bits, in turn, are collected in groups of eight and together make up one byte.

If you look at the previous example of an IPv4 address, the number 192 would be represented in 8 bits as follows: 11000000 (decimal to binary). For IPv6 this works slightly differently and 2a01 is for example equal to 10101000000001 (hexadecimal to binary). While one uses decimal numbers and the other hexadecimal, both IPv4 and IPv6 addresses consist of large sequences of ones and zeros (32 and 128 pieces, respectively).

IPv4 scarcity

You may wonder why it's relevant that an IP address consists of a number of bits. This is due to the maximum number of possible IP addresses. For IPv4, a maximum of 2³² or 4,294,967,296 addresses are possible.

A good 4 billion seems like a good amount, but... they are running out. In the 2010s, the five IP registries began assigning their last 16.7 million IPv4 addresses. In November 2019, the European IP registry Ripe indicated that they no longer had IPv4 addresses. Only when a company stops do (previously used) IPv4 addresses become available again.

This scarcity has been anticipated for some time, which is why IPv6 was launched in 2012. IPv6 uses 128 bits and thus comes with a maximum of 2¹²⁸, or 340,282,366,920,938,463,463,374,607,431,768,211,456 IPv6 addresses. There are so many that it is almost impossible that these addresses will ever run out.

IPv6 is therefore the future of the internet. We fully embrace the adoption of IPv6 and all our services support IPv6. For example, SandboxVPSs even make exclusive use of IPv6. Our government (of the Netherlands) has also obligated all its institutions to fully support IPv6 by the end of 2021. The question is therefore not if, but when everyone worldwide supports IPv6.

Oddly enough, there are also some major IT companies that, despite our requests and fruit baskets, do not yet support IPv6. You might use the services of such companies and in that case we would be happy to help you get the most out of your IPv6 connection via the guides below. Do you use a service that is not yet available via IPv6 and would you like to see a manual or solution? Let us know in a comment below this article.

• Connecting from an IPv4 network to an IPv6 network
• TransIP Github IPv6 proxy
• DockerHub IPv6 beta support

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