Networking · 4 min read · May 12, 2026

IPv4 vs IPv6 — What's the Difference?

The internet is running out of IPv4 addresses. Here's what IPv6 is, why it matters, and how to check which one you're using.

The internet is running out of addresses. IPv4 — the original addressing system — has nearly exhausted its 4.3 billion addresses. IPv6 was created to solve this. Here's what you need to know.

New to IP addresses entirely? Start with what is an IP address? →

What is IPv4?

IPv4 (Internet Protocol version 4) is the original IP addressing system, introduced in 1983. An IPv4 address looks like this: 192.168.1.1 — four numbers between 0 and 255, separated by dots.

IPv4 supports approximately 4.3 billion unique addresses. That sounds like a lot — but with billions of smartphones, computers, smart TVs, and IoT devices all needing addresses, the pool ran out. The last IPv4 blocks were allocated in 2011.

What is IPv6?

IPv6 (Internet Protocol version 6) was designed to replace IPv4. An IPv6 address looks like this: 2001:4860:4860::8888 — eight groups of four hexadecimal digits, separated by colons.

IPv6 supports 340 undecillion addresses (3.4 × 10³⁸). That's enough to give every atom on Earth its own IP address — several times over. We will never run out.

Key Differences

| Feature | IPv4 | IPv6 | |---------|------|------| | Format | 192.168.1.1 | 2001:db8::1 | | Address length | 32-bit | 128-bit | | Total addresses | ~4.3 billion | 340 undecillion | | Security | Optional (IPSec) | Built-in (IPSec) | | Header size | 20 bytes | 40 bytes (simpler) | | NAT required | Yes (often) | No |

Are You Using IPv4 or IPv6?

Most modern internet connections support both IPv4 and IPv6 simultaneously — this is called "dual stack". Your device will prefer IPv6 when available.

You can check which version you're currently using by visiting IPLocator. If your IP address contains colons (like 2001:db8::1), you're on IPv6. If it contains only dots and numbers, you're on IPv4.

Does IPv6 Affect Your Privacy?

IPv6 addresses can be more privacy-sensitive than IPv4. With IPv4, many users share a single public IP through NAT (Network Address Translation) — similar to how a dynamic IP from a pool provides some anonymity. With IPv6, your device may have a globally unique address, making it easier to track across websites.

Modern operating systems use "privacy extensions" to generate temporary IPv6 addresses that change regularly, reducing this risk. A VPN also hides your IPv6 address just as it hides your IPv4 address — important to verify, as some VPNs only tunnel IPv4 and leak IPv6.

IPv6 and DNS

DNS handles both versions — IPv4 addresses are stored in A records, while IPv6 addresses are stored in AAAA records. When your device performs a DNS lookup, it may get back both an A and a AAAA record and will typically prefer the IPv6 one.