When working with VPNs, you may well have come across the terms IPv4 and IPv6. But what lies behind these common technical terms? We will explain the difference between IPv4 and IPV6 protocols, what makes them so crucial and why IPv6 could matter a lot to VPN users.

The meaning of IPv4 and IPv6

So what is IPv4 and IPv6 exactly? Firstly, it’s important to note that both of them are forms of Internet Protocol (hence the “IP”). A protocol is basically a set of rules followed by all the computers on a network.

If followed properly, these rules allow computers with nothing else in common to transfer data, and they are vital in knitting together the billions of computers which make up the World Wide Web.

They also relate to IP addresses, which are designed to be read by these internet protocols, as they move data around the net.

What is IPv4?

As the name suggests, IPv4 was the fourth version of the original Internet Protocol. Even so, it’s pretty old by internet standards, having appeared in 1983 as part of ARPANET, which subsequently became the internet we know.

Ipv4 is still used in packet-switched layer networks, having been developed for use with Ethernet technologies, and it was a natural fit for the expanding internet, which is essentially an expanded ethernet.

The protocol uses 32-bit ethernet/IP addresses in classes labeled by the letters A to E, although A to C addresses are by far the most common (and E addresses still haven’t been used). All of these addresses take the form of 12 digit codes, with four groups of three numbers (e.g.

As we’ll see, the way IPv4 addresses were constructed has caused some problems – creating a limit of 232 local connections and an effective cap on worldwide IP addresses. So a new standard was needed.

What is IPv6?

IPv6 was devised to work around these limitations in the IPv4 protocol. Unlike IPv4, IPv6 is a 128-bit protocol, which provides a far larger set of potential addresses.

IPv6 was drafted in 1998 but the pace of introduction has been slow, and it was only adopted as a new worldwide internet standard in late 2017. That’s how engrained the IPv4 protocol had become. Because of this, the developers of IPv6 ensured that it would work alongside IPv4 – a technical fix which is only now resulting in the new protocol becoming standard.

But what is IPv6 used for? The new protocol isn’t just a way of expanding the web. It has some neat technical benefits too, such as:

  • Improved multicasting
  • A simplified header format
  • No need for Network Address Translation
  • No need to work with DHCP (the Direct Host Configuration Protocol)
  • Much less risk of IP address conflicts
  • More efficient routing
  • Enhanced customization via extensions

All of these improvements are handy for IT professionals and should result in faster browsing for ordinary users as well.

Why are they important?

The task of finding a new standard became increasingly urgent in the 2000s as the number of net users mounted. When the web was first created, nobody anticipated the sheer number of computers it would connect.

The system of giving unique IP addresses to every computer survived, and “peak IP address” loomed in the 2010s as the last original number approached. That’s why the transition from IPv4 to IPv6 became so important – it represented an existential threat to the growth of the internet.

What is the difference between IPv4 and IPv6?

The new protocol uses eight groups of four digits, so an IPv6 example could be 2001:0ce5:34a2:0000:0000:351a:0730:7433. As you can see, the clusters of digits are separated by colons, not dots as in IPv4 addresses.

While IPv4 allowed for 4.3 billion unique codes, IPv6 is much more sophisticated, being capable of generating 340,282,366,920,938,000,000,000,000,000 billion addresses. This vast increase is the main difference between the two protocols.

This might seem like a cosmetic difference, but it has important implications for VPN users.

IPv4 vs IPv6: which is more secure?

IPv6 was created with security in mind and, unlike IPv4, it incorporates end to end encryption as standard. However, when you communicate with an IPv4 address via a VPN, it’s possible that your own address could be “leaked”, putting your security at risk.

You can get around this security risk by disabling IPv6 while using a VPN, but this is time-consuming. Instead, specialist tools are available that can effectively convert IPv6 to IPv4 while you use the VPN – minimizing the risk of leakage.

If you don’t know whether you have IPv6, you can carry out an IPv6 test online. These online tools will give you an instant readout of what kind of IP you are using. They are also handy if you’re wondering what’s my IPv4 address. This should let you know whether you’re at risk of IPv6 leakage.

So, be aware of your IP status whenever you log onto a VPN, and always use a provider who is serious about security.