IPv6 vs IPv4: Key Differences Explained
Both deliver packets across the Internet, but IPv6 was designed decades later to fix IPv4's biggest limitation: not enough addresses.
Side by Side
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Address space | ~4.3 billion | ~3.4×10³⁸ |
| Notation | Dotted decimal 192.0.2.1 |
Colon hex 2001:db8::1 |
| Header | Variable, with checksum | Fixed 40 bytes, no checksum |
| NAT | Common (address sharing) | Usually unnecessary |
| Autoconfig | DHCP | SLAAC and DHCPv6 |
| Broadcast | Yes | No (multicast/anycast) |
| IPsec | Optional | Designed in (still optional in practice) |
Why It Matters
IPv4 ran out of free addresses, so the world relies on NAT to share them. IPv6 removes that constraint, giving every device a globally routable address. Most networks run dual stack (both at once) during the long transition.
In the current deployment this server reaches the Internet over IPv4, so your shown IP is IPv4 today. The subnet calculator and IP converter still accept IPv6 input because they run in your browser. Learn the address forms in IPv6 address types.