IPv4 vs IPv6
Two address formats run side by side on the modern internet. Here is what each one looks like, why both still exist, and which one is most likely carrying your traffic right now.
| Field | IPv4 | IPv6 |
|---|---|---|
| Bits per address | 32 | 128 |
| Address space | ~4.3 billion (2³²) | ~3.4 × 10³⁸ (2¹²⁸) |
| Format | 192.168.1.1 | 2001:0db8:85a3::8a2e:0370:7334 |
| Notation | Four decimal octets, dot-separated | Eight groups of four hex digits, colon-separated |
| NAT used in practice? | Yes — almost universally | Rarely — every device can have a public address |
| Header size | 20 bytes (variable) | 40 bytes (fixed) |
| Built-in encryption? | No (relies on app-layer TLS) | IPsec built in by spec, optional in practice |
| Year standardised | 1981 | 1998 |
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Frequently asked questions
Why was IPv6 invented?
IPv4 has 32 bits of address space, which works out to about 4.3 billion unique addresses. The internet ran out of those in the early 2010s — so the global supply has been recycled, traded, and stretched with NAT ever since. IPv6 has 128 bits, allowing for 340 undecillion addresses (about 3.4 × 10^38) — more than enough to give every grain of sand on Earth its own.
Why is IPv6 adoption taking so long?
IPv6 is not backwards compatible — old IPv4-only servers cannot speak it, and a huge amount of network gear, software, and operational knowledge is built around IPv4. Most of the internet now runs both protocols side by side ("dual stack") rather than migrating cleanly. Your home router, ISP, and the destination site all need to support IPv6 for it to be used end-to-end.
Which is faster, IPv4 or IPv6?
For most users the difference is negligible. IPv6 can be slightly faster because routers no longer need to do NAT, but the path each packet takes through the public internet matters far more than the protocol version. In practice you will not notice a speed difference — what matters is whether your provider has a clean route to the destination.
Is IPv6 more secure than IPv4?
Neither is inherently more secure. IPv6 was designed alongside IPsec for end-to-end encryption, but in practice security depends on the application layer (TLS) and the firewall configuration, just as with IPv4. IPv6 does remove the privacy benefits some users got from NAT — every device on an IPv6 network can have a globally-routable address.
Can I disable IPv6 on my computer?
You can, but you usually should not. Disabling IPv6 on a dual-stack network can cause slow page loads as the system waits for IPv4 fallbacks and breaks some apps that prefer IPv6. The exception is if you suspect IPv6 is leaking around your VPN — in that case, a properly configured VPN will tunnel IPv6 too, or block it cleanly.
Which one is my IP address — IPv4 or IPv6?
Most likely both. Modern home connections give you a dynamic IPv4 address (often shared via NAT with other customers) and a chunk of IPv6 addresses. Our home page shows whichever the request reached us with — usually IPv4 because more of the public internet still uses it as the primary, but IPv6 if your ISP and the route prefer it.