Introduction
If you've looked up your IP address, you may have seen two versions listed: an IPv4 address and an IPv6 address. They look completely different and serve the same fundamental purpose — but one is replacing the other. Here's everything you need to know.
What Is IPv4?
IPv4 (Internet Protocol version 4) is the original IP addressing system, introduced in 1981. It uses a 32-bit number expressed as four groups of decimal numbers separated by dots.
Format: 203.0.113.42
Total possible addresses: ~4.3 billion (2³²)
When the internet was young, 4.3 billion addresses seemed inexhaustible. As of the 2010s, the global pool of available IPv4 addresses was effectively exhausted. This created an urgent need for a new system.
What Is IPv6?
IPv6 (Internet Protocol version 6) is the modern replacement for IPv4. It uses a 128-bit address expressed as eight groups of four hexadecimal characters separated by colons.
Format: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
Total possible addresses: ~340 undecillion (3.4 × 10³⁸)
That's more unique addresses than there are atoms on the surface of the Earth. IPv6 was designed to provide essentially unlimited IP addresses for the foreseeable future.
IPv4 vs IPv6: Key Differences
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address length | 32-bit | 128-bit |
| Address format | Decimal (e.g., 192.168.1.1) | Hexadecimal (e.g., 2001:db8::1) |
| Total addresses | ~4.3 billion | ~340 undecillion |
| NAT required | Yes (to extend addresses) | No (addresses are plentiful) |
| Header size | 20 bytes | 40 bytes (but more efficient) |
| Security (IPSec) | Optional | Built-in |
| Broadcast | Supported | Replaced by multicast |
| Configuration | Manual or DHCP | Auto-configuration (SLAAC) |
| Adoption | ~96% of internet traffic | Growing (~40%+ and rising) |
Why Was IPv6 Created?
The internet grew far beyond what its creators anticipated. IPv4's 4.3 billion addresses were officially exhausted at the IANA (Internet Assigned Numbers Authority) level in 2011, with regional registries running dry in the years following.
IPv6 was designed to:
- Provide an essentially unlimited supply of IP addresses
- Simplify network configuration with auto-configuration
- Improve security with built-in IPSec support
- Improve routing efficiency at scale
- Enable direct device-to-device communication without NAT
What Does an IPv6 Address Look Like?
Full form: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
IPv6 allows some abbreviations:
- Leading zeros in each group can be removed:
2001:db8:85a3:0:0:8a2e:370:7334 - One consecutive run of all-zero groups can be replaced with
:::2001:db8:85a3::8a2e:370:7334
Am I Using IPv4 or IPv6?
Most modern devices support both, using a system called dual-stack. Your device will prefer IPv6 when available, and fall back to IPv4 when not.
You can check which version you're currently using at what-is-my-ip.best — both your IPv4 and IPv6 addresses are shown if available.
Is IPv6 Faster Than IPv4?
In real-world use, IPv6 is slightly faster in many scenarios, primarily because:
- It eliminates NAT overhead
- It enables more direct routing
- Major content delivery networks (CDNs) are optimized for IPv6
However, the difference in everyday use is typically small — under 5ms on most connections.
Is IPv6 More Secure?
IPv6 was designed with IPSec (Internet Protocol Security) as a mandatory feature, while it's optional in IPv4. However, in practice, IPSec implementation is inconsistent even with IPv6.
One privacy note: IPv6 addresses can be more uniquely tied to a specific device because the address pool is so large that NAT (which somewhat obscured individual devices in IPv4) isn't needed. This can have privacy implications on networks that don't implement IPv6 privacy extensions.
Frequently Asked Questions
Q: Do I need to do anything to use IPv6?
A: Probably not. If your ISP supports IPv6 and your router is modern, your devices are likely already using it automatically.
Q: Can IPv6 addresses be hidden with a VPN?
A: Yes, but make sure your VPN supports IPv6. Some VPNs only route IPv4 traffic, leaving your IPv6 address exposed — this is called an IPv6 leak.
Q: Will IPv4 be phased out?
A: Eventually, but not any time soon. IPv4 and IPv6 will coexist for many years through dual-stack and transition technologies.
Conclusion
IPv4 is the legacy system that runs most of today's internet. IPv6 is the future — built for a world with billions of connected devices. Both are in active use, and most modern devices handle both seamlessly. The transition to IPv6 is ongoing and will continue over the next decade.
Check whether your connection is IPv4, IPv6, or both at what-is-my-ip.best.
Last updated: 2026 | Category: IP Address Basics