Is your broadband secure? Check for these 5 common DNS leaks

Many people believe that as long as they are connected to home broadband and using a proxy or circumvention tool, their privacy is completely secure. In reality, in home broadband environments, DNS leaks are almost a “high-frequency issue.”

Many users have even performed DNS leak tests, yet still have no idea where the problem actually lies.

Next, we’ll walk you through the 5 most common reasons why home broadband is prone to DNS leaks, point out the areas most often overlooked, and explain how to properly protect yourself against DNS leaks.

1. Leaving the ISP’s Default DNS Unchanged — the Most Common Pitfall

When home broadband is installed, routers usually default to the DNS servers assigned by the ISP, such as local DNS servers from telecom, unicom, or mobile carriers.

Even if you enable a proxy on your computer or phone, as long as DNS requests still go through the local ISP, it is very easy to cause a DNS leak.

The reason for this type of DNS leak is very simple:

•  Traffic goes through the proxy

•  But domain name resolution does not

As a result, the ISP can clearly see which websites you visit. Recommendations:

•  Manually specify trusted DNS servers at the router level

•  Or enable the “Force DNS through proxy” option in your proxy tool

•  Regularly perform DNS leak tests to confirm the settings are effective

2. Router DNS Hijacking Is More Common Than You Think

Some users have clearly changed their DNS manually, yet still detect leaks. In this case, you should be alert to router-level DNS hijacking, especially if you are using:

•  Old routers

•  ISP-customized routers

•  Devices flashed with firmware from unknown sources

These devices may forcibly hijack DNS requests at a low level. Even if you configure a different DNS on your device, the requests may still be silently redirected.

If you notice:

•  DNS leak test results repeatedly pointing to your local ISP

•  The issue persists across different devices and operating systems

Then the router is almost certainly the source of the problem.

3. Incomplete Proxy Configuration — DNS Not Truly Controlled

This is a pitfall even advanced users often fall into. Many proxy tools only proxy TCP/UDP traffic by default, while DNS handling must be enabled separately.

If you simply “connect and use” without checking these details, DNS leaks are almost inevitable. Common issues include:

•  Fake DNS or DoH not enabled

•  System DNS taking priority

•  Per-app proxying, with browsers not using proxy DNS

After configuration, don’t just check whether your IP has changed. Be sure to run a full DNS leak test plus a browser fingerprint test for double confirmation.

4. Browsers Themselves Can “Quietly Expose” DNS Information

Many people overlook the browser layer. To improve speed, modern browsers often include:

•  DNS prefetching

•  WebRTC

•  Built-in DoH (but incorrectly configured)

If these features are not handled properly, browsers can still cause DNS leaks even when the system itself is secure, potentially exposing your real environment together with browser fingerprints.

Recommended practices include:

•  Applying separate privacy configurations for browsers

•  Regularly performing browser fingerprint tests

•  Using the ToDetect fingerprint tool to verify DNS, IP, and fingerprint consistency

5. Mixed Devices with Inconsistent DNS Settings

In a home broadband environment, the more devices you have, the more complex the issues become.

Computers, phones, tablets, TV boxes, and even smart speakers may all have different DNS configurations.

Some use proxies, some connect directly, and others still rely on default DNS settings. This can lead to:

•  Chaotic DNS request sources within the same network

•  Higher chances of being flagged as an abnormal environment

•  DNS leak protection becoming ineffective

If you care about network privacy, you should at least ensure:

•  Consistent DNS settings on key devices

•  Centralized DNS management at the router level

•  Regular overall environment checks using the ToDetect tool

6. DNS Leak Detection: Common Questions Explained

1️⃣ Is home broadband inherently more prone to DNS leaks than mobile networks?

Yes, statistically it is more likely. The main reasons are:

•  Home broadband is almost always tied to ISP DNS servers

•  Routers play a larger role, increasing hijacking risks

•  More stable network structures make long-term identification easier

In comparison, mobile networks change DNS more frequently, but that doesn’t mean they are fully secure—just that they expose data differently.

2️⃣ What level of DNS leak protection is considered sufficient?

A simple reference standard is:

•  Consistent and trustworthy results across multiple DNS leak tests

•  No obvious conflicts in browser fingerprint tests

•  Controlled differences across devices

If you meet all three criteria, your DNS leak protection is already better than that of most average users.

3️⃣ Does Incognito or Private mode still leak DNS?

Yes—and it’s very common. Incognito mode mainly addresses:

•  Local browsing history

•  Cookies

•  Form data

But it does not equal network-level privacy protection.

DNS requests are still sent through the system or router, so leaks still occur.

This is why many users find that DNS leak tests or browser fingerprint tests still “fail” even in incognito mode.

Final Thoughts:

Many people spend a lot of time researching IPs, nodes, and speeds, yet have never seriously performed a complete DNS leak test—let alone combined it with browser fingerprint analysis to evaluate overall consistency.

Modern risk control and identification systems no longer focus solely on IPs. DNS, fingerprints, time zones, and languages together form your true “network profile.”

If you are using home broadband and care about privacy and stability, it’s strongly recommended that you regularly use the ToDetect fingerprint tool to scan your entire network environment.