DNS Leak Test : How to Perform DNS Leak Test With Accuracy

DNS or Domain Name System is used to translate domain names such as www.example.com to a numerical IP address that are needed to transfer data packets on the internet. When a URL is entered, the browser requests the DNS server for the site’s IP address. Most often, the ISP assigns their customers with a DNS server which is under their own control so that they could record user’s internet activities.

However, when you are connected to an anonymity network such as VPN, it routes your URL request to its own anonymous DNS servers which are unrecognizable for the ISP. But, sometimes your settings keep the default DNS servers enabled instead of anonymous DNS servers, in the presence of VPN connection.

Prevent DNS leak

Nobody likes the interference of any other entity into the private matters of them. Likewise, the internet users also avoid ISP and government snooping into their browsing activities. Therefore, a massive movement towards VPN has been seen.

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Unfortunately, the DNS issues have been witnessed as a cause of leaking IP address and browsing activities to the internet provider even if the VPN is connected. So, to bypass DNS leak issue you must know the preventions and necessary details about DNS system.

What is DNS and How It Works?

There is a Domain Name System or simply DNS so that your device could better communicate with the internet system. Without DNS, the internet isn’t able to operate and show you the desired browsing result.

All the devices have an IP address through which the computer or devices work together and identify each other. This IP also helps the internet or your browser to identify the device to which the results should be sent. The browser is incapable of understanding the words and a human being isn’t so good at memorizing numbers.

For instance, an individual could easily remember a URL in a word form such as www.example.com instead of 123.123.123. Therefore, a DNS system is developed that switches the URL into the IP form.

Here is a simple explanation that why a DNS is important and how it operates to determine the meaning of a query entered on the internet. For instance, you entered a URL www.vpninsights.com into your browser. The browser will then send the request to your DNS server which rapidly transforms it to the IP address which is set up for that domain name. With that IP address, your browser displays you the website information and all this process completes in seconds.

What is DNS Leak?

In regular situations, your browser is sending DNS requests to ISP DNS server which is a default set up in most of the devices. When you enter a URL, the browser sends a request to the ISP notifying that the user wants to access a particular site (the URL you entered). Through this procedure, the ISP is aware of all the browsing activities of a user.

Therefore, to hide the browsing history from ISP, most individuals use anonymous DNS servers such as the VPN server. While being connected to a VPN, the DNS requests should formally be transmitted to the VPN DNS servers, however; sometimes the DNS requests leak to the ISP servers and all the browsing activities are exposed.

The cause of such DNS leak is the default in your VPN and when the VPN is not monitoring the DNS requests. For instance, a VPN might ignore the requests or may use the default settings of the device due to which the DNS requests are exposed to the ISP. The cause of DNS leak is not only due to the fault of your VPN provider, it might be due to the device alteration.

The system reboot, upgrade or clean install is a probable cause of default DNS setting. Yet, some of the browser vulnerabilities such as WebRTC may expose IP address and DNS to the internet provider for which there are different prevention.

On the other hand, the Windows device especially Windows 10 has increased chances of DNS leak. This is because the latest Microsoft operating system tries to make your browsing as fast as possible and therefore, it sends numerous DNS requests through VPN servers from which some might leak to the ISP DNS as well.

The problem is not always regarding your VPN provider however, an updated and efficient VPN could evade the DNS leak issue with continuous monitoring of transmitting DNS requests.

Test DNS Leak

It is important to regularly check your VPN performance through DNS leak test. It is the most convenient way of confirming the vulnerability so that it could be fixed.

The VPNInsight’s DNS test tool lets you check the efficiency of your VPN. The process of checking DNS leak is really simple and quick process. You have to follow these easy steps;

  • Step 1: Connect your VPN and click the button “Execute Test”.
  • Step 2: The site will display DNS results.

From these displayed results you could easily figure out the DNS leaks. If the list contains your real ISP hostname, real IP address or country then the VPN is leaking your DNS requests.

DNS leak is a serious privacy threat because you are kept under the secure feeling, alongside; the anonymity network might be leaking your private data.

How DNS Leaks

Many internet users frequently ask, “What causes DNS Leak?” the answer to this question is “Many reasons”, with some of them being Torrent DNS IP Leak, WebRTC DNS Leak, and VPN IP DNS Leak.

Torrent DNS IP Leak

When you're torrenting, DNS leak assurance is just imperative on the off chance that you need to conceal your connection amongst you and the trackers and UDT from your ISP. Your torrent client can inject your IP address into every packet it sends to the tracker. In this way, torrenting can reveal your DNS with this process being called “Torrent DNS IP Leak”.


WebRTC, short for Web Real-Time Communication is a standard accessed by web browsers like Chrome, Firefox, and Opera to permit the utilization of voice calling or a video visit specifically from a browser. What it likewise does is it perceives the client's actual IP address regardless of which VPN they utilize. There is no chance to get of shielding yourself from WebRTC causing a DNS leak. This vulnerability is named as WebRTC DNS leak.


With a VPN, all activity for anonymous networks is directed through a VPN. So your real association is secured. Despite, your DNS asks for are not bound to an unknown network: it is directed to the local network, which is known to your PC. It is sent straightforwardly to the nearby DNS server without experiencing VPN. The nearby DNS server recognizes what DNS queries you made and that it was you who made them. This is called VPN IP DNS leak.

Prevent DNS leak

DNS leak could be avoided through setting changes to your devices, operating systems, and browsers. It is most probable that your DNS requests are set up to ISP DNS server, so change it to a more secure DNS server.

Change DNS Servers Via Settings

You could get a detailed guide for changing DNS servers into your devices, operating systems, and browsers here.

Mostly the DNS is set up to the ISP server which could be easily switched to any third party server such as free centralized servers, Google DNS or OpenDNS including the paid one. With these third-party servers you could get numerous benefits other than the protection from ISP snooping and hiding internet browsing activities;

  • These DNS servers allow you to enforce parental controls on various websites or content which you think is inappropriate for your child and he/she might not access it.
  • Some of the DNS servers give an access to the restricted content which is normally unavailable for at a specific location or is blocked due to other reasons.
  • Third-party servers such as OpenDNS servers could defend you against the phishing attacks by filtering phishing sites.
  • These servers have improved security features as compared to the ISP servers. Such as, the Google DNS server supports DNSSEC to assure that the entire process of signing DNS requests is secure and accurate.
  • Sometimes a third-party server provides you a faster speed than the ISP DNS server.
  • The DNS level restriction for content or website from your ISP could be evaded through connecting a third-party server instead of using the ISP DNS server.

Use VPN With DNS Leak Protection Feature

We have previously mentioned that despite a VPN connection, DNS request could be transmitted to your internet provider through the ISP DNS server. This is because of a change in default DNS setting due to any reason or when anyone out of numerous DNS requests leaks to the ISP which is caused when the VPN is overlooking the DNS requests.

Also, the reverse in DNS settings to default ISP DNS is sometimes due to the VPN disconnect which occurs most often.

Witnessing the increase in DNS issues, some popular VPN providers have introduced a feature of DNS leak protection which makes sure that all the DNS requests are going through the encrypted and anonymous VPN servers. Therefore, you must check the VPN features before selecting it for yourself.

VPN Monitoring Software

With some VPN monitoring software, the users could get support for fixing DNS leaks. However, you might have to pay for a premium version of the most VPN monitoring software for getting the feature of DNS leak fixing. Therefore, it might not be a consideration for most individuals unless they are keen to know that their VPN connection is totally secure or not.

Block Non-VPN Traffic

You could configure your own firewall in order to restrict the DNS requests only to the VPN servers. All you need to do is to check the network interface settings when you are connected to VPN. In Windows, open command and run ifconfig/all command which will open up the display to view the IP address of your VPN DNS server. Whereas, in Linux, the network interface settings could be viewed through ifconfig command.

Finally, set the firewall rule which hinders all the DNS traffic if it’s not routed towards that specific IP address. Such a command will assure that your domain name requests are only resolved if they are going through VPN DNS.

Disable Teredo

Teredo is a feature of Windows that enables communication across the two IP protocols, the IPv4 and the IPv6. These protocols are present on the internet and with the help of Teredo, the IPv6 capable hosts that are on IPv4 internet could get the complete IPv6 connectivity when they have no native connection to IPv6 network. Yet, the entire Teredo tunneling process is a bit complicated and you can get detailed information here.

Sometimes, Teredo could be the cause of DNS leaks and therefore, you could prevent DNS leaks by disabling Teredo from the settings. To disable Teredo, open command line, and type "netsh interface teredo set state disabled".

However, if you need to enable Teredo at some point then enter “netsh interface teredo set state type=default” in the command line.

DNS Leaks 2018 – Conclusion

DNS leaks are a major concern as they threaten privacy even in the presence of privacy tools such as VPN. This is more concerning because a user is thinking that all his activities are going through an encrypted channel, however, ISP is looking on every act.

Therefore, it is necessary to prevent DNS leak through intelligent VPN selection and other setting changes. Above all, you should regularly run DNS leak test to avoid any threat and unwanted situation.