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

IPv4 and IPv6 are the two versions of the internet's addressing system. IPv4 uses 32-bit addresses (4.3 billion total); IPv6 uses 128-bit addresses (340 undecillion). IPv6 is the better long-term choice, but IPv4 still dominates today.

An IP address works like a street number: it tells the internet where to send data to a specific device.

The global IPv4 pool ran out in 2011. Regional registries followed over the next decade, with the last (Europe) running out in 2019. That is why IPv6 exists.

What is IPv4?

IPv4 launched in 1981 and is still the most widely used IP version.

Its 32-bit format allows 4.3 billion unique addresses.

That was enough in the 1990s. Today's device count has far outstripped it.

People now run phones, TVs, consoles, and smart devices all at once. IPv4 ran out of new public addresses in 2019.

To stretch the remaining addresses, networks use two workarounds: NAT and DHCP.

NAT lets every device on your home network share one public IP. DHCP hands out short-lived private addresses to each device as it connects.

What is IPv6?

IPv6 launched in 1998 as a replacement for IPv4.

IPv6 uses 128-bit addresses instead of 32-bit, giving it 340 undecillion possible addresses. That is enough for every device on Earth, many times over.

IPv6 also built in security features that IPv4 only added later.

IPv6 includes IPsec, a protocol that encrypts data between devices and verifies each device's identity. IPv4 can use IPsec too, but it is optional.

In practice, you still need HTTPS for full encryption. But IPv6 makes it harder for attackers to fake a device's address or insert themselves into a connection.

Switching is not as simple as updating software.

IPv6 and security: what changes

IPv6 is more secure by design. The problem is that most networks have not fully switched yet.

Enabling IPv6 on one server is not enough. Your firewall, logging, and network layout all need updates.

Many firewalls and logging tools do not handle IPv6 by default. That gap can open attack paths, and fixing it often means redesigning your network.

Running both protocols at once (the most common setup today) can create security gaps if one side is not patched.

That is why IPv4 is still everywhere, even though IPv6 is the better option.

If you use a VPN, check that it supports IPv6. Some VPNs do not.

If your VPN does not handle IPv6, your device may connect to an outside DNS server and leak your real IP address.

Check that your VPN and devices both support IPv6 before you rely on it.

Use a free IP leak checker (such as ipleak.net) to verify that no IPv6 address is leaking.

Adoption is slow. Most businesses only switch when they replace hardware.

IPv4 vs IPv6: which should you use?

You will not notice a speed difference between IPv4 and IPv6.

In some cases, converting traffic between the two protocols adds a small amount of delay.

For most home users, the choice is made for you by your ISP. For businesses, it depends on your network.

IPv4 still works fine. IPv6 is the better long-term choice and should be enabled where your equipment supports it.

Until every device supports IPv6, make sure your firewall handles both protocols so one does not become a weak point.