Why Does Changing DNS Still Lead to Leaks? 99% of Users Miss This Hidden Setting

Why do I still see leaks after switching several DNS servers? Many people struggle for a long time because most overlook a key setting — one that is even more likely to cause leaks than the DNS itself.

You may think you changed the DNS, but the system/browser may still be using the default resolution method. Combined with browser fingerprinting, WebRTC, IPv6, and other factors, leaks can still occur.

Next, let's explain in detail why DNS leaks still happen and how to properly check and fix them!

1. The Core Reason Why DNS Changes May Not Work: You Overlooked “Forced” Resolution

1. The Operating System Might “Bypass” the Default DNS

Both Windows and macOS have DNS caching, DNS optimization, DNS prefetching, and other mechanisms.

Especially when IPv6 is enabled, the system may prioritize IPv6 DNS and bypass your set IPv4 DNS.

2. Browsers Have Their Own DNS Settings

●  Chrome has Secure DNS (DoH)

●  Firefox enables encrypted DNS by default

●  Edge may not sync with the system

●  Some domestic browsers use their own DNS by default

That is to say, changing DNS in the system does not guarantee that the browser will comply.

3. Routers and ISPs Might Force DNS Hijacking

Especially in some regions, broadband may have:

●  DNS redirection

●  ISP-level transparent proxy

●  IPv6 forced resolution

This means that whatever DNS you enter, it may be overridden by the network.

2. DNS Leaks Come in Multiple Forms: Did You Test Correctly?

Many people only test traditional DNS, forgetting that DNS leaks can occur in multiple dimensions. Common forms include:

1. IPv6 DNS leaks

2. Leaks caused by inconsistent DoH/DoT configurations

3. Browser built-in DNS leaks

4. WebRTC leaks (often appearing together with DNS leaks)

Therefore, it is recommended to perform a complete DNS leak test to identify the real source of the leak.

3. You Might Think It’s a DNS Leak, but Browser Fingerprints Could Be Exposing You

This is something many people are completely unaware of. Even if you perfectly fix DNS leaks, as long as the browser fingerprint is stable, websites can still track you.

That is, even when you change DNS, switch proxies, or use private mode, the other side can still recognize you through fingerprint algorithms.

At this point, you need to use a browser fingerprint detection tool to see which data is being exposed.

4. Recommended Tool — ToDetect Browser Fingerprint Checker

If you suspect that the issue is not a DNS leak but an “information-level” leak, you can directly check the data exposed by your current browser using the ToDetect Fingerprint Checker.

This is much more convenient than testing multiple websites and helps you determine whether the recognition comes from a DNS leak or a fingerprint leak.

5. How to Truly Prevent DNS Leaks? These Settings Must Be Done Together

1. Disable IPv6 or Manually Set IPv6 DNS

If IPv6 is not needed, it is recommended to disable it:

IPv6 often secretly uses the ISP’s default DNS.

2. Manually Set Your Desired DNS

●  Chrome → Settings → Privacy → Secure DNS

●  Firefox → Network Settings → Enable Encrypted DNS

Otherwise, the browser may select the DNS service automatically.

3. Also Modify DNS on the Router

Otherwise, all devices in your home will be redirected by the router.

4. Use Tools for Complete DNS Leak Testing

●  Test IPv4 DNS separately

●  Test IPv6 DNS separately

●  WebRTC leak test

●  DoH leak test

Ensure that every link in the chain has no leaks.

Conclusion

Many people think changing DNS is enough, but in reality DNS leaks are just the most basic form of privacy exposure. Browser fingerprints are now the main way websites identify users.

To truly maintain privacy, you must pay attention to: DNS configuration correctness, browser feature leaks, fingerprint consistency, and overall network behavior.

It is recommended to regularly use DNS leak testing + browser fingerprint detection + ToDetect Fingerprint Checker for multidimensional checks.