If you've ever looked at an IP address, it probably looked something like 203.0.113.42 — that's an IPv4 address. But the internet is gradually moving to a newer generation called IPv6, which looks like 2001:db8::1. Here's what's different, why the change is happening, which one you're probably using, and what it means for privacy and for the problems you may run into.
What is IPv4?
IPv4 is made of four numbers between 0 and 255, separated by dots (like 192.168.1.10). Under the hood that is a 32-bit number, which provides about 4.3 billion unique addresses (232). That seemed enormous in the 1980s, but it has run out in practice: the central registry handed out its last free blocks in 2011, and the regional registries followed over the next years. New customers now often receive a shared address or buy one second-hand. Part of the answer was private addresses and NAT, and later CGNAT, which lets many customers share one public IPv4 address.
What is IPv6?
IPv6 was designed to remove that shortage. It is a 128-bit number written as eight groups of four hexadecimal digits, separated by colons:
2001:0db8:85a3:0000:0000:8a2e:0370:7334That structure provides roughly 340 undecillion addresses (2128, about 3.4×1038) — enough to give every device on Earth, and every grain of sand, many addresses of its own. Because the addresses are long, there are two shortening rules:
- Leading zeros in a group can be dropped:
0db8becomesdb8. - One run of all-zero groups can be replaced by
::(only once per address).
So 2001:0db8:0000:0000:0000:0000:0000:0001 is written 2001:db8::1.
| IPv6 range | Meaning |
|---|---|
::1 | Loopback (like 127.0.0.1) |
fe80::/10 | Link-local: automatic, works only on the local link |
fc00::/7 | Unique local: the IPv6 counterpart of private addresses |
2000::/3 | Global unicast: normal public addresses |
2001:db8::/32 | Reserved for documentation and examples |
Key differences
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Format | Dotted decimal (192.168.1.1) | Colon-separated hex (2001:db8::1) |
| Address count | ~4.3 billion | Effectively unlimited |
| NAT (address sharing) | Usually required | Usually unnecessary |
| Configuration | Manual or DHCP | Automatic (SLAAC) or DHCPv6 |
| Typical home subnet | /24 (254 hosts), see CIDR | /64 (a huge block per network) |
| Broadcast | Yes | No — multicast instead |
| Support today | Universal | Growing, not yet universal |
Why hasn't everyone switched to IPv6 yet?
A full migration requires updating routers, ISPs, servers, and legacy software, and the two protocols cannot talk to each other directly. Instead of a switch-over day, the internet runs dual-stack: devices and servers have both kinds of address and use whichever works, preferring IPv6 when it is available. Other bridges exist — tunnels, and translators such as NAT64 — for networks that are IPv6-only. Meanwhile, NAT and CGNAT keep IPv4 alive, with the side effects of shared reputation and no inbound connections (port forwarding fails).
Which one am I using?
Open the Show-IP.ir homepage. The address shown is the one your device used to reach the site: dots mean that connection was IPv4, colons mean IPv6. Many networks run both, so the same device can show either one depending on the site. You can also look on the device itself — ipconfig on Windows, ip -6 addr on Linux — as described in the guides for Windows and Linux; IPv6 lines are called "IPv6 Address" or inet6.
Privacy and security: what changes with IPv6
- Privacy extensions. Modern systems create temporary IPv6 addresses that rotate, so the address websites see is not a permanent fingerprint of your device.
- No NAT is not "no firewall". With IPv6 every device can have a public address, so the router's firewall must still block unsolicited inbound traffic. Home routers do this by default.
- VPN leaks. A VPN that only handles IPv4 can leave IPv6 traffic outside the tunnel and reveal your real address; test it with the VPN leak check.
- Location. IPv6 does not reveal a more exact location than IPv4; it still maps to a provider and a rough region (what an IP can reveal).
Frequently asked
Is IPv6 faster than IPv4?
Not by itself; speed depends on the network path. It can feel better where IPv4 sits behind CGNAT, because IPv6 traffic avoids that extra translation.
Should I disable IPv6?
Usually no. Disabling it can break some services and does not make you safer. If a specific problem points to IPv6 (for example a VPN leak), fix it in the VPN or router first.
Will IPv4 stop working?
No. IPv4 will be around for many years; the two will coexist.
Key takeaways
- IPv4 is older, more common, and limited to about 4.3 billion addresses.
- IPv6 is newer, written in hexadecimal with colons, and effectively never runs out of addresses.
- Most networks today run both simultaneously (dual-stack).
- NAT and CGNAT are what let IPv4 networks keep working despite the address shortage.
- If an IP result on Show-IP.ir has colons it is IPv6; test your VPN for IPv6 leaks.