IPv4 vs IPv6: what are they and what’s the difference?

IPv4 vs IPv6

An Internet Protocol address, also known as an IP address, is the address given to a computer or device to enable it to communicate on the internet. And they’re incredibly important. After all, without an IP address, you wouldn’t be able to send and receive information. In other words. Without IP addresses, the internet would be impossible.

And there are two types of IP addresses: IPv4 and IPv6. But what does this mean? What’s the difference between IPv4 and IPv6? We’re putting them head to head in our in-depth IPv4 vs IPv6 review to tell you everything you need to know about these two different internet protocol address types.

What is IP address?

An IP address is a set of numbers that’s assigned to a device so that it can be identified on the internet. It enables data to be sent and received from your device. Even if you use a VPN to get a fake IP address, you still need one to use the internet.

Example of ipv4 vs ipv6

The two versions of IP addresses are IPv4 and IPv6. And while both will provide you with an IP address to enable you to surf the internet, there are a few key differences between IPv4 and IPv6 you’ll need to be aware of. Read on to find out what they are and how they differ.

What is IPv4?

IPv4, or Internet Protocol version 4, was developed back in the early 1980s. And despite the invention of the more modern IPv6, IPv4 still routes most of the world’s traffic. IPv4 uses a 32-bit address and can support a maximum of 232 (or more than 4 billion) IP addresses.

An IPv4 address is made up of four numbers, each ranging from 0 to 255. These are separated by full stops. It’s very likely that your IP address will be an IPv4 address.

Here is an example of an IPv4 address: 

Of course, the fact that IPv4 has been around for nearly 40 years does present a problem. IPv4 has a limit of 4.3 billion addresses, which sounds impressive. And back in the early 80s, this was seen as far more than enough. But of course, as the internet grew across the world, we quickly began to run out of IPv4 addresses. And by the mid 1990s, engineers had to come up with solutions to create more IP addresses.

Of course, nowadays, everyone uses several devices to connect to the internet, including smartphones, laptops and tablets, as well as traditional desktop computers. And with the Internet of Things meaning more devices need IP addresses than ever before, developers have had to come up with a more permanent solution to this problem.

What is IPv6?

Internet Protocol version 6, or IPv6, is the sixth iteration of the Internet Protocol and was created because the world was in danger of running out of IPv4 addresses. IPv6 works in much the same way as IPv4 – by providing unique, numerical IP addresses needed for devices to send and receive data on the internet.

However, as you might imagine, an IPv6 address is a lot longer than an IPv4 address, which means you can create a lot more unique IP addresses than you can with IPv4. And when we say a lot more, we really mean it. IPv6 uses a 128-bit address and can provide 340 undecillion IP addresses, while IPv4 is limited to 4.3 billion IP addresses.

For those interested, an IPv6 address is made up of eight groups of four hexadecimal digits. These are separated by colons rather than full stops.

An example of an IPv6 address looks like this: 2001:0db8:82a3:0000:0000:4a2e:0370:7337

IPv6 was first introduced back in the late 1990s in the hope that it would replace IPv4 before we ran out of IP addresses. However, the transition from IPv4 to IPv6 has been slow. And the main reason for this is that it costs time and money to upgrade all the routers, servers and switches that have depended on IPv4 for so long. So, while IPv6 is ready to go, it’s taking a long time to roll out.

Here are some of the benefits of IPv6:

  • Routing is made more efficient by reducing the size of routing tables. 
  • Support for multicast rather than broadcast allows bandwidth-intensive packet flows to be sent to many destinations at the same time, which saves bandwidth.
  • Auto-configuration means that configuration tasks, such as IP address assignment and device numbering can take place automatically.
  • Security features that provide data integrity, authentication and confidentiality are baked into IPv6.

IPv4 vs. IPv6: what’s the difference?

As well as having a lot more IP addresses, IPv6 has more functionality than IPv4. For one thing, IPv6 supports multicast addressing, which helps to enable bandwidth-intensive data, such as multimedia streams, to be sent to several destinations at the same time. This reduces bandwidth and makes things run more smoothly.

For the main differences between IPv4 and IPv6, take a look at our table:

Address32 bits (4 bytes)128 bits (16 bytes)
Packet size576 bytes required, optional fragmentation1280 bytes required without fragmentation
Packet fragmentationRouters and sending hostsSending hosts only
ChecksumHas a checksumDoesn’t have a checksum
DNS recordsPointer (PTR) records, IN-ADDR.ARPA DNS domainPointer (PTR) records, IP6.ARPA DNS domain
Local subnet group managementInternet Group Management Protocol (IGMP)Multicast Listener Discovery (MLD)
IP to MAC TesolutionBroadcast ARPMulticast Neighbour Solicitation

IPv6 also helps devices stay connected to several networks at once. This is because the configuration capabilities enable the hardware to assign multiple IP addresses to the same device automatically.

You’ll also find that IPv6 comes with a brand new feature called auto-configuration. This lets a device generate an IP address as soon as you switch it on. The device will then look for an IPv6 router. And if it finds one, the device can generate a local address and a globally routable address at the same time. With IPv4 networks, meanwhile, the process of adding devices usually needs to be done manually.

Having said all this, IPv6 isn’t perfect. In fact, at the moment, it’s actually no faster or more secure than IPv4. And, because IPv4 is so much more established than IPv6, you might find IPv4 more suited to your needs. After all, IPv6 doesn’t yet work on all VPNs. And some systems struggle with handling IPv6 routing.

IPv4 vs IPv6 security: which one is safer?

IPv6 was made to be secure. IP Security (IPSec) is a series of IETF security protocols that promote authentication, security and data integrity that’s built into IPv6.

Back when IPv6 first launched, it required the encryption of internet traffic using IPSec, which is a popular encryption standard. This makes IPv6 secure as encryption scrambles the content of your internet traffic so that anyone intercepting is unable to decipher it.

However, IPSec can also be implemented on IPv4, which means that, in theory at least, IPv4 has the potential to be just as safe as IPv6. But of course, as it can be expensive to implement, this hasn’t seen widespread uptake.

Naturally, we expect to see an increase in IPSec use as we transition from IPv4 to IPv6. But until that happens, some experts assert that IPv6 users are actually more at risk of security issues than IPv4 users. Some internet service providers use transition technologies, such as IPv6 tunnels, that can leave users vulnerable to cyber security threats. Hackers target IPv6 tunnel users with reflection attacks and packet injection.

Of course, as this transition to IPv6 is likely to take many more years to complete, these transition methods will probably be in use for a while yet. So it’s worth bearing in mind that the transition technology could leave you vulnerable to hacking.

So, when it comes to security, which one is better? IPv6 will ultimately end up being more secure. But right now, they’re both more or less equally safe.

IPv4 vs IPv6 speed: which one is faster?

In speed tests, IPv4 and IPv6 delivered the same speed in direct connections. As a matter of fact, if anything, IPv4 was occasionally slightly quicker.

In theory, IPv6 should be slightly faster as cycles don’t have to be wasted on NAT translations. However, IPv6 also has larger packets, which can make it a little slower in some cases. So if anything, IPv4 may perform slightly faster. But there’s really not that much difference in it.

IPv6 and VPNs

Most VPNs operate on IPv4. If you’re using a VPN that uses IPv4 and you try to access a website that runs on IPv6, your VPN may redirect your traffic to an external IPv6 DNS server. This means that your traffic would exit its secure VPN tunnel, so your traffic will no longer be completely private.

This could make you susceptible to a DNS leak, which may mean your original IP address and, by extension, your location could be exposed. It could also disrupt the service of the website you’re trying to access. This also means your internet service provider is able to monitor your online activity, thereby rendering your VPN effectively useless.

However, some VPNs will offer IPv6 leak protection. So if you’re using IPv6 and you want to make sure your data is safe from leaks while you’re using your VPN, it’s worth making sure your VPN supports this.

You can find out more about IPv6 leak protection a bit further on in this guide.

VPNs with IPv6 support

The majority of VPNs do not support IPv6 at the moment. But there are a few that do. Here’s a list of VPNs that support IPv6:

  • CyberGhost is one of the only VPNs that supports 100% of IPv6 addresses. In a pledge to consumers, CyberGhost promised that all of its servers will support IPv6, even if internet service providers don’t offer it yet.
  • PureVPN offers IPv6 support along with IPv6 leak protection to keep your online activity safe and secure at all times.
  • NordVPN has integrated IPv6 leak protection to prevent data leaks.
  • Perfect Privacy provides the option of an IPv6 address even if your provider does not offer it.
  • hide.me VPN uses a dual stack configuration to deliver IPv6 connectivity to support both IPv4 and IPv6.
  • AirVPN has deployed full IPv6 support to its VPN servers.


Why do we use IPv4 instead of IPv6?

The main reason IPv4 is still more widely used than IPv6 is because it takes a lot of time and resources for the transition from one to the other. After all, it’s quite costly and time consuming to upgrade all the routers, servers and switches that rely on IPv4. And, while some companies have begun to make the switch, others have opted for the cheaper and simpler option of sticking with IPv4.

What is the key difference between IPv4 and IPv6?

The main difference between IPv4 and IPv6 is that IPv6 has a lot more IP addresses than IPv4. IPv4 has 4.3 billion IP addresses, while IPv6 has 340 undecillion IP addresses. This means that IPv6 will be the version we all eventually transition to, as the world needs a lot of IP addresses and IPv4 just simply doesn’t have enough for all the devices that need them.

What is IPv6 leak protection?

Lots of VPNs offer IPv6 leak protection, which works to stop your data from being exposed while you’re using IPv6. It often does this by automatically disabling IPv6 traffic while keeping you connected to your VPN. That way, no IPv6 traffic can leak out over your standard internet connection, thereby keeping all your online activity private and secure.

How many IPv4 addresses are there?

IPv4 and IPv6 are limited. IPv4 contains 4,294,967,296 unique addresses. IPv6 is a lot spacious in this regard and has 3.4×10^38 addresses. That’s almost a duodecillion!

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