Imagine I connect to example.com, change my IP address using my VPN service, and then remain on example.com in my browser. Meanwhile I open some other sites and eventually switch off my VPN service. Therefore I start using my initial IP again and continue using example.com. Can example.com detect the change of IP address? Does it matter if I received any activity from example.com (incoming message, likes, ...) while I was connected to my VPN?

  • I've edited your question fairly heavily for clarity, but believe I've retained your original question. If you don't like my changes you can edit it again or revert my changes. – Conor Mancone Feb 12 '20 at 14:06
  • yes, they can detect the change in IP address. I think it's pretty common to log an IP when a user logs in or when the user takes certain actions, but not so much for every request. On the other hand, some sites log everything, even mouse movements... so they might even constantly poll for ip. – pcalkins Feb 12 '20 at 22:57

When you enable/disable a VPN your IP address changes but your browser doesn't. A web application can easily track you regardless of your IP address by using cookies and a variety of other methods. In fact, the IP address doesn't matter at all for tracking purposes - a user on a mobile phone will have their IP address change frequently by simply walking out of their home and switching from WIFI to mobile data.

As a result switching to a VPN won't do anything to hide your previous history from a web application unless you take additional steps. The only thing that a VPN gives you some privacy from is your ISP.

You can easily confirm this yourself. Login to a website, connect to your VPN, and then continue using the website. If you are still logged in then they still know how you are despite turning on your VPN. Then turn your VPN off again and I'm sure you'll find you are still logged in.


The loaded page can contain some code that periodically polls data from the web site. This doesn't need to be a secret function. It can be a pretty normal one, e.g. the web site checks if there are any new messages on the server, e.g. it displays the online status of your friends. On each such request the server sees your current IP.

If the loaded web page does not communicate with the web site in the background, then it will not know if you have changed IP to VPN and back.

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