IPv4 vs IPv6: What's the difference and which one is better?

An IP (internet protocol) address is a fundamental element of how the internet works.
Traditionally made up of numbers such as 123.12.34.56, every single device connected to the internet will be assigned an IP address to allow it to be identified and located.
This is not much different than a street address as it allows information to be sent to that virtual location from anywhere in the world.
But as internet usage and technology's connectivity continue to rapidly increase, there is a need to change from the original standard IPv4 to IPv6.
But what are the differences between the two protocols, and which one is better for you?

History of IPv4

IPv4 was invented in the late 1980s and remains the most commonly used method of directing online traffic to the correct locations.
The combination of numbers that can be understood by IPv4 result in 4.3 billion potential IP addresses.
While this may have been plenty in the 80s and 90s, the sheer number of internet-connected devices available today goes far beyond what could have been imagined previously.
With people using multiple connected devices every day, from phones and tablets to smart TVs, games consoles, voice assistants and smart light bulbs, we are hurtling towards IPv4's address limit – which could mean that no new devices would be able to connect to the internet.
To combat this risk, it is common for many devices to connect using a dynamic IP, that is, an IP address which is assigned when the device connects to the internet and can be re-assigned when the device disconnects.
Previously, every device received its own static IP which meant that many addresses were left unused when devices were not connected.

History of IPv6

The development of a replacement system resulted in the launch of IPv6 in 1998.
By extending IP addresses from 32 bit to 128 bit, the maximum number of combinations increased significantly, from 4.3 billion to 340 undecillion, relieving pressure on the IPv4 system.
IPv6 also offers many improved security options over its predecessor.
For example, IPv6 runs end-to-end encryption as standard. While encryption can be used with IPv4, it is an extra that is not consistently used.
If IPv6 was used universally, the level of encryption could significantly hinder Man-in-The-Middle (MITM) attacks.
In addition, it would make IP spoofing in general incredibly difficult. This is due to improvements in securely verifying the host's identity, improving trust in connections and limiting a hacker's ability to impersonate a host.
However, the switchover is not as simple as upgrading your software.

How does this affect security?

On paper, IPv6 is by far the most secure of the two options, but the difficulty comes in its implementation.
There are huge differences between the two, meaning that it is not as simple as enabling IPv6 on your server.
Firewalls, security logging, and network setups may not be IPv6-enabled by default – with the resulting difference creating opportunities for attacks and your network structure will likely have to be redesigned from the ground up.
Similarly, a gradual transition would mean using both IPv6 and IPv4 at the same time, potentially causing gaps in your security.
With adoption being such a huge task, and partial adoption not being safe, it is clear why IPv4 remains prevalent despite the many additional benefits of IPv6.
Most security-conscious users will be familiar with the benefits of increased security and anonymity that a virtual private network (VPN) can offer, but not all VPN services use IPv6.
In fact, if you try to access an IPv6 address, the VPN may use an IPv6-compatible DNS server that is outside of their network, resulting in a potential data leak or exposing your real location.
This can be avoided by checking the compatibility of your devices and services.
You can also use an IP address checker and DNS leak checker to see whether your data is being exposed.
As always with new security measures, there will come a time when new vulnerabilities are discovered and exploited.
Systems will continue to evolve in order to become more secure, and wider implementation of IPv6 is the next step.
However, while this is happening, it is at a very slow rate. Many businesses and services are only upgrading when their existing routers and switches need to be replaced.

So which is best?

Despite IPv6's many benefits, users are unlikely to notice any improvements in speed and performance of their internet connections.
In fact, there may be increased latency caused by the conversion of data between IPv6 and IPv4.
While it would be ideal for IPv6 to be a universal solution, the realities of implementation mean that your choice will depend on your setup.
IPv4 continues to serve its purpose, but IPv6 is clearly a marked improvement in security and should be adopted where possible.
However, until IPv6 is a uniform standard, great care has to be taken to ensure that devices using different IP protocols are not inadvertent weaknesses in your network.