Public vs private IP addresses
A public IP can be routed across the internet. A private IP is intended for use inside a local network. Your laptop or phone can have a private address at home while websites see a different public address from your router or provider.
The short version
Most home and office networks use private addresses internally and one or more public addresses externally. Network Address Translation, usually shortened to NAT, lets many private devices share a public IPv4 address when they connect to the internet.
That is why the address shown by a website can be different from the address shown in your Wi-Fi or Ethernet settings.
Which IPv4 ranges are private?
The familiar private IPv4 ranges are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. They can be reused independently inside different networks because internet routers do not treat them as globally reachable addresses.
The range 100.64.0.0/10 is also not globally routable, but it is not an RFC 1918 private range. Providers commonly use it for carrier-grade NAT, where several customers share public IPv4 capacity.
What about IPv6?
IPv6 does not need NAT in the same way IPv4 commonly does. Devices can have globally routable IPv6 addresses as well as local-use addresses. Unique local addresses use fc00::/7, while link-local addresses use fe80::/10 and only work on the local network segment.
A device can have several IPv6 addresses at the same time, so seeing more than one address is normal.
See the address websites see
IPGetter shows the public address your current connection presents to the internet, including its IP version, ASN and approximate network location.
Why can two devices show the same public IP?
If two devices are behind the same router, NAT can make both appear to websites under the same public IPv4 address. The router keeps track of the individual connections using ports and internal state so replies return to the correct device.
With carrier-grade NAT, even multiple households can appear behind the same public IPv4 address. That is one reason an IP address alone should not be treated as a unique person or device identifier.
Which address should you use when troubleshooting?
- Local device-to-device problem: start with the private or local address shown on the device.
- Website or internet service: check the public address the service sees.
- Port forwarding: confirm the router has a public address rather than a CGNAT address.
- IPv6 issue: check whether the connection is actually using IPv6 and whether the destination has an AAAA record.
Prefer the command line?
See the public IP and address family websites can currently see.
> ip
Run in Terminal ->