# Proxy shows two different IP addresses? Check the family

> A proxy that shows an IPv4 address on one checker and an IPv6 address on another is usually one dual-stack exit. Rotation only shows within one family.

Source: https://mosaicbrowser.com/blog/two-ip-addresses-one-exit

## IPv4 from one probe, IPv6 from the other: one exit, not two

A proxy that shows an IPv4 address on one checker and an IPv6 address on another is usually one dual-stack exit. Rotation only shows within one family.

![v4 + v6: Two addresses, one exit, three wrong verdicts](https://mosaicbrowser.com/covers/two-ip-addresses-one-exit.webp)

When a proxy shows two different IP addresses, look at their shape before anything else. If one is IPv4 and the other is IPv6, you are most likely looking at one exit that has both kinds of address, reached over IPv4 by one checker and over IPv6 by the other. That is not rotation. Rotation only shows when two answers of the same family disagree, and a leak only shows when one of them is your own.

## Why a proxy shows two different IP addresses

An exit on a modern residential connection is often dual-stack: the household has one IPv4 address shared by everything in the house, and IPv6 addresses for the devices themselves. When your browser goes through a proxy, it does not pick the family. Chrome hands the hostname to an HTTP or SOCKS5 proxy and lets the proxy resolve and connect, so the exit decides, based on which addresses the checker's server publishes and what the exit's network prefers. Two checkers, two answers.

There are three cases, and they need different responses:

| What the two checks show | What it usually means | What to do |
| --- | --- | --- |
| One IPv4, one IPv6, neither yours | one dual-stack exit | nothing; compare like with like |
| Two different IPv4 (or two IPv6) | rotation, or a sticky session that expired | check the session settings |
| One of them is your own address | a leak | find which request went around the proxy |

Mosaic is a desktop app

Email yourself the link and open it on your computer.

[How it works: Provider minting](https://mosaicbrowser.com/features/proxy-providers)

## The check that called a sticky session a pool

We learnt the first row by getting it wrong. Mosaic's proxy check samples the exit twice on purpose: a location lookup at ip-api over plain HTTP, and a tunnel probe to Cloudflare over HTTPS. Two different addresses from those two requests is how a rotating endpoint gives itself away, so the check compares them.

On one residential exit the two requests left by different families. The answers looked like this (real addresses replaced with documentation ranges):

```
ip-api      (HTTP)  203.0.113.44
Cloudflare  (TLS)   2001:db8:7c3e:5dc4::d565

```

The comparison was a string inequality, and `203.0.113.44` is not `2001:db8:…`. It called the proxy a rotating pool three checks in a row, while both addresses stayed identical from check to check. The exit reputation report then told the operator that their sticky session was "one sample of the pool" and advised pinning the session, which they had already pinned. That was a confident wrong answer, on screen, about a proxy that was working exactly as sold.

## Two families are not evidence

The fix is one rule. `rotated()` now returns false unless both addresses are the same family and differ. An IPv4 address and an IPv6 address cannot be compared, so they say nothing about rotation in either direction; we do not count them as proof that the exit is stable either. It is the same rule we apply to a gateway that times out once: silence is not a measurement, and neither is a comparison that could never have come out equal.

If you check by hand, do the same. Use one checker, ask it twice a minute apart, and compare the IPv4 answers with each other. Many checker pages show IPv4 and IPv6 on separate lines, which makes that easy. A sticky session that changes its IPv4 address between two such checks did rotate, and the usual reasons are in [what a sticky session expiry looks like](https://mosaicbrowser.com/blog/sticky-session-expiry-symptoms). A rotating port that ignores your session token is a separate problem, covered in [why a session does not hold on a rotating port](https://mosaicbrowser.com/blog/session-token-on-rotating-port).

## When the second address is yours

Most "my proxy shows two IPs" threads are about the third row, and there the cause is usually not the web request at all. With an explicit proxy, Chrome's page loads go through it. WebRTC does not have to: it sends UDP, and Chrome's SOCKS5 support carries TCP only. A leak test that shows your home address next to the proxy's has usually caught WebRTC. In Mosaic, a profile with a proxy runs with a WebRTC policy that stops UDP from going around the proxy, which is on by default.

The address a site sees decides more than the IP column. Mosaic draws a profile's timezone, language and geolocation for its proxy's measured exit, and each profile minted from a [proxy provider](https://mosaicbrowser.com/features/proxy-providers) gets its own session, so [forty profiles get forty exits](https://mosaicbrowser.com/blog/forty-profiles-forty-exits) rather than one.

## Questions

### Why does my proxy show two different IP addresses?

If one is IPv4 (four numbers with dots) and the other IPv6 (groups of hex with colons), it is usually one exit with two address families, reached over different ones by two checkers. If both are IPv4 and they differ, the proxy rotated or the session expired. If one is your own address, something is leaking.

### Does an IPv6 address on a proxy check mean my proxy is leaking?

Not by itself. Through an HTTP or SOCKS5 proxy, Chrome lets the proxy resolve and connect, so the family the site sees is the exit's choice. Compare the IPv6 address with your own connection's: if it is yours, it leaked; if not, the exit has IPv6.

### How do I check whether a proxy is rotating?

Ask the same checker twice, a minute apart, and compare addresses of the same family. Two different IPv4 addresses from one sticky session is rotation or expiry. An IPv4 address beside an IPv6 one proves nothing either way.

### How does Mosaic decide a proxy rotated?

Its proxy check samples the exit twice, over HTTP and over HTTPS, and counts it as rotated only when both answers are the same family and differ. Addresses of different families are treated as not comparable.

## Related

[What an expiring sticky session looks like from inside a browser](https://mosaicbrowser.com/blog/sticky-session-expiry-symptoms): A sticky session expired on our proxy: the browser showed tunnel errors, the check a healthy proxy in another state. Neither said expired.

[Same proxy session on multiple profiles: forty profiles, forty exits](https://mosaicbrowser.com/blog/forty-profiles-forty-exits): The same proxy session on multiple profiles means one exit IP for all of them. A batch of ours did it in September 2026; now every profile mints its own.

[A session token on a rotating port is a 400, not a no-op](https://mosaicbrowser.com/blog/session-token-on-rotating-port): "Can not use -session- on rotating ports" means the port, not the username, decides stickiness. We had written the opposite, until we asked the gateway.

[Provider accounts: one gateway line, one exit per profile](https://mosaicbrowser.com/features/proxy-providers): Paste your proxy seller's gateway line once and Mosaic mints a separate session for every profile, so each one browses from its own exit address.

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## Mosaic, on your own computer

The browser this blog is about: its own Chromium, fingerprints from real machines and a proxy exit per profile. Free holds 3 profiles. Pro is $49 a month for any number.

Mosaic is a desktop app

Email yourself the link and open it on your computer.