How IP Addresses Work
IPv4 vs. IPv6: A Detailed Comparison
IPv4 and IPv6 do the same job — identifying devices on the internet — but they differ in size, format, and capability. Here's how they stack up.
Address size
The headline difference is length. IPv4 uses 32-bit addresses (about 4.3 billion total). IPv6 uses 128-bit addresses (around 340 undecillion). This is the whole reason IPv6 exists: to escape IPv4's address shortage.
Format
- IPv4: four decimal numbers, like
192.0.2.1. - IPv6: eight groups of hexadecimal digits, like
2001:db8::1, with zero-compression to keep them shorter.
Network Address Translation
Because IPv4 addresses are scarce, most networks hide many devices behind one public address using NAT. IPv6 has so many addresses that every device can have its own public one, so NAT is largely unnecessary — which can simplify direct connections between devices.
Configuration
IPv4 devices usually get their address from a DHCP server. IPv6 supports that too, but also allows stateless address autoconfiguration, where a device can generate its own valid address using information from the local router — no central server required.
Other differences
- Header: IPv6's packet header is simplified and fixed-length, which can speed up routing.
- Security: support for the IPsec security framework was designed in from the start (though it is used optionally).
- Broadcast: IPv6 drops IPv4-style broadcast in favor of more efficient multicast.
Which one are you using?
Probably both. Most modern connections are dual-stack, holding an IPv4 and an IPv6 address at the same time and using whichever a given service supports. Check IP Ducky and you may see both listed — clear proof that the two systems coexist on today's internet.