IPv4 vs IPv6
Both are versions of the Internet Protocol. IPv4 is the original 1980s design; IPv6 is its successor with a vastly larger address space. Most connections today use both.
| IPv4 | IPv6 | |
|---|---|---|
| Length | 32 bits | 128 bits |
| Possible addresses | about 4.3 billion | about 3.4 × 1038 |
| Format | 203.0.113.25 | 2001:db8:85a3::8a2e:370:7334 |
| Notation | 4 decimal numbers 0–255 | 8 groups of 4 hex digits; zeros can be shortened with :: |
| Address sharing | common (NAT, carrier-grade NAT) | rarely needed; every device can have a global address |
| Configuration | DHCP or manual | automatic (SLAAC) or DHCPv6 |
Why IPv6 exists
Four billion addresses looked endless in 1981 but not with phones, laptops and smart devices for billions of people. The regional registries handed out their last regular IPv4 blocks in the 2010s. Providers coped with NAT, where one public IPv4 address is shared by a whole home or, with carrier-grade NAT, by many customers. IPv6 removes that scarcity.
Do you have IPv6?
Open What is my IP. If the address contains colons (:) your browser reached us over IPv6; if it is four numbers separated by dots, over IPv4. Browsers prefer IPv6 when both sides support it, so seeing IPv4 usually means your provider or router has not enabled IPv6.
Is one faster or safer?
Neither is inherently faster; speed depends on the route. IPv6 can feel quicker on mobile networks because it avoids carrier-grade NAT. Security is similar: both rely on your router's firewall and on encryption (HTTPS) at higher layers. With IPv6, devices are reachable by a global address, so the router firewall must block unsolicited inbound traffic, as virtually all home routers do by default.
Private ranges
IPv4 private networks use 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6 uses unique local addresses (fc00::/7) and link-local addresses (fe80::/10), which every interface has automatically.