Fixed a DNS Leak? Do These 3 Checks, or You’re Not Done Yet.

Many people feel a false sense of security after fixing DNS leaks. Honestly, the most problematic issues often occur after the "fix."

This is because DNS is not a one-time setup. If even one component in your environment, browser, or system is misaligned, you may experience a situation where "everything seems fine on the surface, but leaks are still happening."

Based on practical experience, I will explain in detail: how to re-verify if a DNS leak fix was successful and some commonly overlooked details during the verification process.

1. First, understand: What is a DNS leak, and why must it be tested?

If you are using a "proxy network," but DNS requests secretly go back to your local ISP, this is called a DNS leak.

Once a DNS leak occurs, it can cause several issues:

•  Your real IP location is exposed

•  The proxy environment is identified as "not clean"

•  Some websites or platforms may trigger risk controls

•  Even with a proxy enabled, access may still be restricted

Therefore, fixing a DNS leak is only the first step. DNS leak testing and detection are the real verification steps.

2. After fixing a DNS leak, don’t rush to use it

A common mistake is immediately logging into accounts or running tasks right after fixing a DNS leak.

The recommendation is: test first, then use. Testing mainly involves two parts:

•  Check if DNS is still leaking

•  Check if the overall browser fingerprint is "clean"

3. How to test for DNS leaks? Step by step

1️⃣ Use a professional DNS leak testing website

After fixing a DNS leak, you can use DNS leak testing tools to verify. Pay attention to the following points during testing:

•  Whether the DNS server's country matches the proxy IP

•  Whether your local ISP (e.g., Telecom, Unicom) still appears

•  Whether multiple abnormal DNS nodes are mixed

If the results still show your real location or domestic DNS, it can be basically confirmed: the DNS leak fix was not thorough.

2️⃣ Test multiple times, don’t trust a single check

DNS leak detection must account for "occasional occurrences." It is recommended to:

•  Clear the browser cache

•  Restart the browser

•  Run 2–3 consecutive DNS leak tests

Only if the results are consistent each time can it be considered reliable.

4. Often overlooked: Browser fingerprints can also "reveal DNS behavior"

It’s important to emphasize: DNS is not just a system-level issue; browser fingerprints are also crucial.

Even if the DNS leak is fixed correctly, an abnormal browser fingerprint may still be detected. In such cases, browser fingerprint testing is necessary.

5. Use ToDetect fingerprint tool for comprehensive verification

In practice, I recommend combining DNS leak detection + browser fingerprint testing. Using tools like ToDetect, you can check in one go:

•  Whether the DNS resolution path is abnormal

•  Whether WebRTC is leaking

•  If IP association information conflicts

•  If the browser fingerprint appears overly real or inconsistent

This comprehensive approach is much more reliable than just checking DNS leak results.

Many people see "no problem" with DNS, but when checked with ToDetect, DNS behavior does not match the browser environment, posing a higher risk.

6. After passing DNS leak tests, pay attention to these details

Successfully fixing a DNS leak does not mean you are "done forever."

•  Do not switch proxy nodes frequently

•  Keep the browser environment as consistent as possible

•  Ensure system DNS settings are not automatically reverted by security software

•  Regularly recheck DNS leak results

Especially after system updates or browser upgrades, it is necessary to redo DNS leak tests.

Summary

DNS leaks are never a "fix once and done" issue; they require long-term attention to network details.

Whether using basic DNS leak tests or combining ToDetect fingerprint tools for a full browser fingerprint check, the essence is to confirm one thing: your network request paths are truly aligned with your expectations.

Spending a few extra minutes to test for DNS leaks can prevent unnecessary problems later. Network environment may seem like a small detail, but it determines success or failure—the more attention you give, the fewer pitfalls you'll encounter.