Where the address comes from
When your browser requests this page, the server reads the source address of the connection. On a hosted site the request passes through a reverse proxy first, so the server takes the client address from the header that proxy sets, then strips the ::ffff: prefix that dual-stack sockets attach to IPv4 peers. The result is the address every website you visit sees.
A server can only see one address family per connection. If your browser connected over IPv6, the server has no way to learn your IPv4 address, and the reverse is also true. For that second address the page asks an echo host from your browser: ipv4.icanhazip.com or api.ipify.org for IPv4, ipv6.icanhazip.com or api6.ipify.org for IPv6. Each host is reachable on one family only, so its reply is your address on that family.
That request must come from your browser: a server-side request would report the server's own address. Each echo host gets five seconds, and a reply counts only if it parses as an address of the expected family.
Reading the network details card
The IPv4 address and IPv6 address rows show both families side by side. The family you connected with is the one in large type, and the other row is filled by the echo check. ISP and Organization come from the owner record and often differ: ISP is the company operating the access network, while Organization may be a customer, a reseller or a cloud tenant holding the block.
ASN pairs the autonomous system number with its registered name, for example AS64496 Example ISP (a number reserved for documentation). Location (approx.) gives a city and country from the owner's registration data, which is why it can name a city far from your desk. The card titled What websites also see repeats the User-Agent and Accept-Language headers your browser sent.
When the result looks wrong
A city that is not yours is the most common complaint. IP geolocation is only as good as the owner's registration records and the provider's routing: a mobile carrier may route all traffic through one regional gateway, so every subscriber in a country appears to be in the same city. Treat the location as a region hint, never as a street address.
An address that changes between visits is normal for a home line with a dynamic lease. A provider shown as a hosting company or a VPN brand means your traffic exits somewhere else, and the pill changes to VPN / proxy or Data centre / hosting. Unknown in the ISP, ASN and Location rows means the owner lookup failed or timed out. Refresh usually fixes it.
- Private address detected: the server saw an RFC 1918, loopback or link-local source, so there is no owner record or PTR to show.
- An error instead of an address: the server has not been told which proxy header carries the client address and refuses to guess.
Carrier-grade NAT and shared addresses
Many mobile and some broadband providers no longer give each customer a public IPv4 address. They place subscribers behind carrier-grade NAT, so thousands of people share the address shown here while the private side uses 100.64.0.0/10. You cannot open a port to a device behind CGNAT, and an allow-list built on that address admits every customer sharing it.
IPv6 usually sidesteps this. If the IPv6 address row shows a global address beginning with 2 or 3, each device on your network has its own public address and a firewall rule can name it precisely. For a full report on any address, including one that is not yours, use IP lookup. To see the provider first rather than the address, use What is my ISP.