Net Readout

Guide · Updated 28 October 2026

IPv4 and IPv6 explained

Many connections now have two public addresses: an older IPv4 one and a newer IPv6 one. Here is what each is, which one websites see, and why it matters if you use a VPN.

Short answer

IPv4 is the original address system and ran short of addresses. IPv6 is its much larger replacement. Most connections now have both, and websites see whichever one your device uses to reach them. See both of your addresses.

Two kinds of address

IPv4
  • Looks like 203.0.113.42: four numbers from 0 to 255.
  • 32 bits long, so there are 4,294,967,296 possible addresses.
  • Usually shared: your router gives all your devices one public IPv4 address.
IPv6
  • Looks like 2001:db8:4a4a::1: groups of hexadecimal digits separated by colons.
  • 128 bits long, so there are about 340 undecillion possible addresses (3.4 × 1038).
  • Each device can have its own public address.

The example addresses above come from ranges set aside for documentation, so they belong to no one.

Why IPv6 exists

About 4.3 billion IPv4 addresses are not enough for every phone, computer and connected device in the world. Providers stretch them by sharing one address between many homes or phones. IPv6 removes the shortage, so providers have been adding it alongside IPv4 rather than replacing IPv4 overnight.

Which one sites see

When both you and a website support IPv6, your device usually connects over IPv6, so the site sees your IPv6 address. Sites that only support IPv4 see your IPv4 address. That is why two sites can show you two different addresses, and why our IP page shows both.

Privacy and VPNs

  • IPv6 privacy addresses. Most systems use temporary IPv6 addresses that change over time, so your device is harder to track by address alone.
  • VPN leaks. Some VPNs carry only IPv4 traffic. Your IPv6 traffic can then go around the tunnel and show your real address. Test your VPN checks for this, and the VPN guide explains the fix.
  • Location. Location databases can place your IPv4 and IPv6 addresses differently. Why your IP location can be wrong.
Speed testDownload, upload, latency and jitter. Health checkBrowser updates, encryption, proxies, VPN leaks, injected content. What sites seeEverything a website can read about your device. Test your VPNRun once with your VPN off and once on, and see what changed.
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