Your router settings show two addresses, and one of them looks like a jumble of letters and colons.
Short answer on IPv4 vs IPv6: same job, different scale. IPv4 has about 4.3 billion addresses and ran out years ago. IPv6 has practically unlimited ones. For browsing you won’t notice which you’re on, so leave both switched on.
Where the difference bites is VPNs, proxies and servers. We checked 12 big sites and found five that still can’t be reached over IPv6 at all.
IPv4 vs IPv6 at a glance
IPv6 is the newer, bigger version of the Internet Protocol, and it runs alongside IPv4 rather than replacing it overnight.
| IPv4 | IPv6 | |
|---|---|---|
| Address size | 32 bits | 128 bits |
| Looks like | 192.168.1.10 | 2001:db8::8a2e:370:7334 |
| Total addresses | About 4.3 billion | About 340 undecillion (3.4 × 1038) |
| Header | 20 to 60 bytes, with a checksum | Fixed 40 bytes, no checksum |
| Getting an address | DHCP or set by hand | Configures itself (SLAAC), DHCPv6 optional |
| Sharing addresses | NAT almost everywhere | Every device can have its own public address |
| Finding neighbours | ARP | Neighbor Discovery (NDP) |
The first three rows are the reason IPv6 exists. The rest is housekeeping the designers fixed while they were in there.
Why did the internet need a second address system?
Because IPv4 ran out. The central pool that hands out addresses to regions emptied in February 2011, and North America’s registry hit zero in September 2015.
Four billion sounds like plenty. Then count every phone, laptop, TV, camera, server and cloud machine on the planet.
So how is everyone still online?
NAT, mostly. Your router holds one public IPv4 address and shares it with every device at home, each of which gets a private address like 192.168.1.10. Many mobile carriers go further and share one public address across many customers.
A proxy swaps your visible address in a similar way, for one app at a time instead of the whole house. Our guide to proxy servers explains how.
Scarcity also has a price now. Since February 2024, AWS charges $0.005 an hour for every public IPv4 address, in use or idle. That’s about $3.65 a month per address, or roughly $730 a month for a fleet of 200 servers, before you’ve run a single workload. IPv6 addresses aren’t part of that charge.
Our take: if you run servers, IPv4 is now a line item on your bill. If you only browse, the shortage is someone else’s problem, solved quietly by NAT.
What do the two addresses actually look like?
An IPv4 address is four numbers from 0 to 255 separated by dots. An IPv6 address is eight groups of four hexadecimal digits separated by colons.
Written out in full, an IPv6 address is long: 2001:0db8:0000:0000:0000:ff00:0042:8329. Two rules shorten it:
- Drop leading zeros in each group, so
0db8becomesdb8and0042becomes42. - Replace one run of all-zero groups with a double colon. You can only do this once per address, or nobody could tell how many zeros went where.
Apply both and that address becomes 2001:db8::ff00:42:8329. We ran it through Python’s ipaddress module to check, and that’s exactly what it printed.
Scale is where your intuition breaks. A single home network in IPv6 is usually a /64, which holds 18.4 quintillion addresses. That one subnet is 4.3 billion times bigger than the entire IPv4 internet. ISPs often hand a home a /56, which is 256 of those subnets.
Two prefixes help when you read your own settings:
- Starts with 2 or 3: a global address that works on the public internet.
- Starts with fe80: a link-local address that only works on your own network. Every IPv6 device has one, even when it has no IPv6 internet at all.
What changes under the hood?
The packet itself got simpler, even though the address got four times longer.
- A fixed 40-byte header. IPv4’s header varies from 20 to 60 bytes. IPv6 fixed it at 40 and moved the rarely used options into optional extension headers.
- No header checksum. Every IPv4 router recalculates one on every packet. IPv6 leaves error checking to the layers above, so routers do less work.
- No fragmenting in the middle. IPv4 routers can split a packet that’s too big. In IPv6 only the sender can, and every link must carry at least 1,280 bytes.
- Devices configure themselves. With SLAAC, a device hears the router’s prefix and builds its own address. No DHCP server required.
The bigger header costs a little. In a standard 1,500-byte packet, TCP over IPv4 carries 1,460 bytes of data and TCP over IPv6 carries 1,440. That’s 1.4% less payload, which you’ll never feel on a web page.
Is IPv6 faster or safer than IPv4?
Not reliably faster, and only safer if your router is set up properly. The protocol isn’t the deciding factor in either case.
Speed: the route matters more than the version
Some networks route IPv6 more directly, especially mobile carriers that skip a layer of NAT. Others send it the long way round. The path to the site decides your speed, not the version number.
Your device also doesn’t commit blindly. When a site has both address types, browsers and operating systems use a method called Happy Eyeballs.
The standard recommends giving IPv6 a head start of about 250 milliseconds. If IPv6 hasn’t connected by then, the device starts an IPv4 attempt in parallel and uses whichever answers first. A broken IPv6 path costs you a quarter of a second, not a dead page.
Security: NAT was never a firewall
On IPv4, NAT hides your devices as a side effect: nothing from outside can reach a private address it doesn’t know about. On IPv6, each device can have a public address, so your router’s firewall has to block unsolicited incoming traffic on purpose.
Most home routers do this by default. Cheap or old ones are worth checking.
Privacy improved too. Early IPv6 built addresses from your network card’s hardware ID, which made a laptop trackable across networks. Modern Windows, macOS, Android and iOS use randomised temporary addresses that change regularly instead.
What we found when we checked real sites
How much of the web would you lose on IPv6 alone? On 11 November 2026 we asked a public DNS resolver for both record types on 12 big sites. A records hold IPv4 addresses; AAAA records hold IPv6 ones.
| Has an IPv6 (AAAA) address | IPv4 only, no AAAA record |
|---|---|
| google.com, facebook.com, wikipedia.org | github.com, amazon.com |
| netflix.com, reddit.com, cloudflare.com | x.com, openai.com |
| droidcrunch.com (through Cloudflare) | wordpress.com |
Five of the 12 had no IPv6 address at all. A device with only IPv6 and no translation service couldn’t open GitHub, Amazon or ChatGPT’s home page directly.
Our own test machine showed the reverse problem. It had an IPv4 address, an fe80 link-local address and no IPv6 route out, so every IPv6 connection we tried failed at once. That’s normal on many cloud and office networks, and invisible while you browse.
Google’s counter puts the share of its users arriving over IPv6 at 46.64% (9 November 2026). So about half of visitors have IPv6, while plenty of popular sites still don’t offer it.
Real-world tip: if you run a WordPress site behind Cloudflare, you probably already serve IPv6 without lifting a finger. Our domain got its AAAA records that way.
Where IPv6 trips people up: VPNs and proxies
Here’s the catch most IPv4 vs IPv6 explainers skip. Mixing the two is where privacy tools quietly fail.
The IPv6 leak
Some VPNs only tunnel IPv4. If your ISP gives you IPv6 too, a site that supports it can be reached outside the tunnel, and it sees your real IPv6 address. Your IPv4 address looks hidden, so you think you’re covered.
There are two clean fixes: a VPN that tunnels IPv6 properly, or one that blocks IPv6 while connected. NordVPN takes the second route on its apps: it shuts off the IPv6 interface and sends only IPv4 through the tunnel. Our VPN tunnel explainer shows what a tunnel does and doesn’t cover, and our kill switch guide covers the other common leak.
To test your own setup, connect your VPN and run the leak checks in our proxy and leak testing guide. If any address from your ISP shows up, IPv4 or IPv6, you have a leak.
IPv6 proxies: cheap for a reason
IPv6 proxies cost far less than IPv4 ones because the addresses are nearly free. They come with two real limits.
- Sites without IPv6 can’t be reached. From our check, that rules out GitHub, Amazon, X and OpenAI for an IPv6-only proxy.
- Blocks hit whole ranges. Since one customer can own billions of addresses, many sites rate-limit or ban by /64 rather than by single address. A thousand IPv6 proxies from one /64 can look like one user.
For accounts and guarded sites, IPv4 still does the heavy lifting. Our residential proxy explainer covers why an address’s owner matters more than its format. Choosing between the two IPv4 options? Our residential vs datacenter proxies guide settles it.
How to check whether you’re using IPv6
It takes under a minute, and the only thing to look for is an address starting with 2 or 3.
Find your IPv6 address
Pick your system
-
Step 1 of 4
Windows
Open Command Prompt and type ipconfig. Look under your Wi-Fi or Ethernet adapter for an IPv6 Address line that isn’t the Link-local one.
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Step 2 of 4
macOS
Open System Settings, then Network, then your connection, then Details, then TCP/IP. An IPv6 address there that starts with 2 or 3 means you’re on IPv6.
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Step 3 of 4
Linux
Run ip -6 addr in a terminal. A line with scope global means IPv6 internet. Only fe80 lines with scope link means no IPv6 internet, which is what our test machine showed.
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Step 4 of 4
Phone
On Android, check Settings, About phone, Status, IP address. On iPhone, tap the info icon next to your Wi-Fi network. Mobile data often has IPv6 even when home Wi-Fi doesn’t.
If you see only IPv4, your ISP or router hasn’t enabled IPv6. Nothing is broken. Check your router’s admin page for an IPv6 setting before you call your ISP.
Should you turn IPv6 off?
No, not as a fix for anything general. Microsoft explicitly advises against disabling IPv6 on Windows, and some system features expect it to be there.
Turning it off makes sense in two narrow cases. Your VPN leaks IPv6 and offers no setting to block it, or one specific old device misbehaves on IPv6 and the maker confirms it. Fix the device or the VPN, not the whole network.
Running a site or a server? Do the opposite and add IPv6. If you’re comparing VPN protocols next, our WireGuard vs OpenVPN comparison covers which ones handle IPv6 tunnels cleanly.
Frequently asked questions
Is IPv6 better than IPv4 for gaming?
Sometimes. On networks that run IPv4 through carrier-grade NAT, IPv6 can avoid strict NAT types that block hosting or voice chat. Ping depends on the route to the game server, though, so test both.
Can an IPv4 device talk to an IPv6 device?
Not directly. The two protocols don’t understand each other’s packets. Networks bridge them with dual stack, where devices run both, or with translation services like NAT64 that let IPv6-only phones reach IPv4-only sites. Most home networks use dual stack.
Why does my phone have an IPv6 address but my laptop doesn’t?
Mobile carriers adopted IPv6 early because they ran short of IPv4 addresses fastest. Your phone on mobile data gets IPv6 from the carrier, while your laptop on home Wi-Fi depends on your ISP and router. Enabling IPv6 on the router usually fixes it.
Does IPv6 reveal my exact location?
No more than IPv4 does. Both point to your ISP and a rough area. Modern devices use temporary IPv6 addresses that change regularly, which makes it harder to follow one device over time. A VPN that handles IPv6 hides both.
Will IPv4 ever be switched off?
Not any time soon. Too many sites, apps and corporate networks still depend on it, as our check of 12 big sites showed. Some mobile networks already run IPv6-only internally and translate to IPv4 at the edge, so the switch-off happens network by network.
Is the IPv4 vs IPv6 choice something I set in my browser?
No. Browsers don’t have a switch for it. Your operating system picks per connection using Happy Eyeballs, based on which addresses the site offers and which path answers first. You control it only through router, operating system or VPN settings.
Do I need IPv6 for my website?
You don’t need it to be reachable, since IPv6 visitors still get IPv4 through dual stack. It’s still worth adding. Most CDNs such as Cloudflare add it for you, and on cloud hosts it avoids paying for extra IPv4 addresses.
The bottom line
IPv4 vs IPv6 comes down to scale: a 32-bit system that ran out of addresses, and a 128-bit replacement with room to spare. For everyday browsing they’re interchangeable, and Happy Eyeballs picks the faster one for you.
Leave IPv6 on at home. Make sure your VPN handles IPv6 or blocks it. Use IPv4 proxies for anything a site guards closely. Your next step takes a minute: run the leak test with your VPN connected and see which addresses show up.
