DNS leak? Here is what you should know

Domain Name System (acronym: DNS) is the backbone of online browsing. So, what is a DNS leak?

Permit me to begin by explaining what the DNS job entails. DNS’s fundamental operating concept is that it resolves unique domain names such as “facebook.com” to their associated IP addresses through a DNS server.

When a user enters a domain name into their browser to access a certain website, the device communicates with the DNS server to get the IP address. The user cannot ultimately access the targeted website unless the DNS server accepts the request and provides the IP address.

Now, returning to the first question.

What is a DNS leak?

All internet traffic should be routed via the VPN network when connected through a Virtual Private Network. When a query is sent, that is, when someone wishes to visit a certain domain name, it is routed via an encrypted tunnel to the VPN providers’ DNS servers.

A DNS leak is a kind of security breach in which requests are sent to the user’s Internet Service Provider (ISP). A DNS leak is a collective method for screening and monitoring DNS servers at the ISP level by examining the public DNS servers used to translate internet hostnames to IP addresses.

DNS leakage is a problem between a device and its DNS resolvers that compromises the user’s privacy by transferring all data and queries via an unencrypted or, in other words, less secure DNS request over the VPN.

When inquiries and other non-encrypted portions of your internet traffic are broken, not only is the user’s privacy compromised, but any foreign or third party may simply view and intercept the queries. As a consequence, the user’s ISP and DNS server are aware of which websites are visited and which services are used by the user’s device.

If a service does not route all of your traffic via the internet, it is insecure. There is no way to determine if a DNS breach occurred without doing a DNA leak test. Numerous internet sites provide DNS leak testing. Essentially, it is a VPN security test that verifies for leaks and the possibility of a third party monitoring your online activity.

We are living in an era of net neutrality and internet security. While browsing the internet, users should not have to worry about their privacy.

However, such breaches do occur. There are many methods to avoid them, and each issue they cause has a remedy, which you will learn about later in this article.

To combat the issue of DNS leaks, several internet service companies have established their own public DNS servers, such as Cloudflare’s public DNS servers. Public DNS servers are considered to be more secure than private DNS servers and are known to be capable of avoiding DNS leaks.

What causes a DNS leak?

There are many causes for the phenomenon(s) that result in a DNS leak and compromise a user’s online activity security. They are:

  • DNS leaks that occur when a VPN is a “split-tunnel” VPN, which allows traffic to be routed via the local network platform even while the VPN is enabled.
  • Leaks are more likely to occur if a user has recently modified or reset their system settings.
  • Manually configuring a Virtual Private Network (VPN) often results in DNS leaks.
  • When a user utilizes a VPN service that lacks control over its DNS servers or has adequate protection against DNS leaks, this results in a security breach.
  • Microsoft announced a new feature in Windows 8 called “Smart Multi-Homed Name Resolution.” Eventually, this resulted in the system’s handling DNS queries differently, allowing the DNS request to go across all of the computer’s public network ports. While this new method improved the speed with which a DNS query is completed, it raised the danger for VPN users since the functionality introduced by Windows 8 did not limit traffic to the DNS servers of the individual VPN providers. The likelihood of a security breach as a result of a DNS leak has grown with time.
  • The DNS settings for a specific user’s network are incorrect. This may compromise the user’s online security and result in a DNS leak.
  • Another cause of DNS leakage is that the user’s Internet Service Provider may be using transparent DNS proxies that are more susceptible to security breaches.
  • There may be problems with a user’s IPv4 or IPv6 transition, which is why an imminent DNS leak is occurring.

These factors, either together or separately, result in the interception of online information by third parties on the network as a result of a DNS leak.

How do DNS leaks happen?

We know that a DNS leak occurs when information about a user’s online activities is revealed to a third party, who may then see your browser activities and compromise the user’s browser and device’s security.

We know what a DNS leak is. But how does it work?

VPN software hides a user’s IP address and replaces it with an arbitrary one to guarantee the system’s security. Since this random IP address changes continuously, a third party will be unable to trace a specific user’s online activity.

If a user uses their ISP’s DNS servers rather than a DNS server or a VPN, the DNS server keeps a record of all the user’s requests. It allows the user’s browser, or anybody attempting to unlawfully intercept and monitor their online activity, to quickly get access to the records by tracing the IP address through the connection between the user’s ISP and DNS server.

Frequently, a situation occurs in which the VPN provider is unable to conceal the IP address and encrypt all system data. As a consequence, they inadvertently expose the user’s original IP address to anybody attempting to intercept unencrypted queries and traffic between the user’s browser and the appropriate DNS server. This will always result in a DNS leak.

Problems DNS leaks lead to and the solutions to solve them and their respective solutions

Problem 1: Improper configuration of network

The most frequent cause of DNS breaches is the internet being connected through several networks.

For instance, an individual who switches between public hotspots and a home router. The device needs to be connected to a local network.

Without appropriate settings, there is a significant probability of data breaches.

When a new network is connected, the DHCP settings are updated to appoint a DNS server to handle the user’s lookup requests. It may be an ISP issue or one that is not adequately guarded or protected.

Even if this is connected to a VPN on the network, there is a high probability that the DNS request will escape the encrypted tunnel and result in an undesirable DNS leak.


The most appropriate and straightforward approach would be to utilize an independent DNS server, such as OpenDNS or Google Public DNS.

These DNS servers are configured in such a way that DNS requests are routed via the VPN rather than directly from the user’s computer.

There are still criteria that must be met; specifically, it is extremely reliant on the VPN provider, the protocol being used, and the effect of altering the configuration on the same.

As a result, it is essential to consult the VPN client’s help for specific instructions.

Problem 2: IP Version 6

IPV4, or Internet Protocol version 4, has been phased out in favor of IPV6, or Internet Protocol version 6.

IPV6 is nothing more than a combination of eight sets of four characters, each of which may be a letter or a number.

The internet’s shift from IPV4 to IPV6 is causing a slew of difficulties, particularly for VPNs.

Any requests from the client’s computer for IPV4 to IPV6 conversion are sent via a dual-stack tunnel.

This conversion bypasses the VPN tunnel, exposing and unprotecting the user’s personal data.


VPN services that by default support IPV6 traffic do not encounter any issues.

Those without such support, on the other hand, should ensure that appropriate IPV6 arrangements have been provided.

It is advisable to choose one that fully supports the protocol.

Bear this in mind before using a commercial VPN.

Problem 3: Teredo

Teredo is a feature of the Windows Operating System that comes pre-installed.

It is a technique that aims to improve and increase the interoperability of IPV4 and IPV6 networks.

It is a technology that enables the seamless coexistence of IPV4 and IPV6. This allows the understanding, transmission, and reception of V4 addresses over V4 connections.

This, however, might be seen as a glaring security flaw for VPN users.

Teredo, being a tunneling protocol, often takes over the encrypted tunnel of the VPN, escaping it and therefore generating undesired DNS leaks.


The answer to this dilemma is as simple as ABC.

Fortunately, Teredo can be easily deactivated from inside Windows.

One needs to open the command prompt and write:

“netsh interface teredo set state disabled”

A few issues may occur as a result, but it is usually preferable to deal with such little issues than to risk DNS leaks.

How can DNS leaks be prevented?

Always remember that prevention is always preferable to treatment. Several preventive measures include the following:

Changing the settings to a delegated, trusted, autonomous DNS server: A user’s network adapter or router may be configured to alter their TCP or IP settings, allowing for the specification of especially trustworthy and secure DNS servers through their IP addresses.

Blocking non-VPN traffic with the help of a firewall or VPN: The “IP Binding” option automatically prevents any traffic that does not pass via the VPN.

Performing DNS leak tests at regular intervals: You must conduct DNS leak tests on a frequent basis.

Usage of VPN ‘monitoring’ software: This may add additional cost, but it is worth it since it enables a quick look at a DNS check.

Altering or changing the VPN if necessary: If necessary, continue modifying or modifying the VPN.

How can NordVPN combat the danger of DNS leaks?

NordVPN is the best VPN for preventing DNS leaks. NordVPN is a VPN service provider that offers private and encrypted connections that enhance the privacy and security of your internet data. NordVPN offers VPN services to both consumers and businesses. NordVPN will not impose any limitations on your VPN service. You may connect to any NordVPN server anytime you want, without any restrictions or limitations.

To prevent DNS leaks from becoming a target, the easiest option is to utilize a VPN service that has a built-in DNS leak repair.

Another way to avoid DNS leaks is to manually change the DNS server address. Rest assured that your ISP is not monitoring your communications. Additionally, open sources such as Google Public DNS and Open DNS offer information on DNS servers.

This technique is more beneficial since it protects your connection and greatly improves performance.

How to modify DNS Server on a Windows OS?

1. Start the Control Panel, then click the Networks and Settings option.

2. Then, click Change Adapter Settings.

3. Locate the major connections and right-click to choose Properties.

4. Locate the Internet Protocol Version 4 (TCP/IPv4) tab. Select it, then choose Properties.

After selecting that – Use the following DNS server addresses option and enter the proper addresses.

5. Select the OK option and the connection will restart. It’s a good idea to save the old DNS server in case you need to reverse it afterward.

How to conduct a DNS leak test?

The issue is determining how to detect a DNS leak and how to test for one.

By default, all interactions between the web and the DNS server are unencrypted and accessible to everyone. If your Internet Service Provider (ISP) or a hacker intercepts these messages, they may simply trace your entire online activity.

When you visit a website that tests for DNS leaks and sees your ISP’s IP address among the results, there is a DNS leak.

Visit https://www.dnsleaktest.com/ for more information. This is a simple solution to verify. Double-click the URL, first without the VPN switched on and then with the VPN turned on.

If you’re concerned about a DNS leak while using a VPN, take these steps:

  • Switch off VPN.
  • Visit https://www.dnsleaktest.com/ for more information.
  • Take note of the data sent as a response on the page, which contains the ISP’s IP address and geographic location.
  • Now, activate the VPN and choose a new geographical location.
  • Rerun the DNS leak test using the webpage for DNS leak detection.

You’ll see a variety of different IP addresses, ISP names, and geographic regions. If, however, you are able to determine your original ISP’s IP address and other information, the VPN has a DNS leak.

Select your chosen geographic location and activate the VPN.

All of the information changed as a result of the DNS test. This indicates that the VPN does not have a DNS leak.

As a result, such VPN services have become essential. NordVPN is one of the most cost-effective and speedy VPN service providers on the market. Additionally, NordVPN offers users the address of a DNS server.

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