The term DNS Leak refers to when your network configuration inadvertently gives away information about your connection. It is most commonly used in the context of connecting to a virtual private network or VPN.
What is DNS?
DNS is the domain name system of the internet. It's a bit like a phone book or your telephone contacts, where instead of remembering a telephone number, we can just use a name. In the same way, DNS allows us to use facebook.com or bbc.co.uk instead of having to use their IP addresses. As such DNS is an essential part of your internet connection and without it, your internet would effectively stop working.
What is a DNS leak?
When you connect to a VPN, your public IP address changes. This gives you a level of privacy and anonymity as you are no longer using your local IP address and if you have chosen a good VPN provider (ahem!), your VPN IP address will not be easily traced back to you as an individual. The VPN connection should also securely route all your DNS queries via the VPN as well, however, if your system is not configured correctly, your system can 'leak' DNS requests back to your local DNS provider and this can give away your location and local internet service provider, as well as your DNS queries.
How do I test for a DNS leak?
We've created a special DNS Leak Test page which allows you to test your configuration and see if your DNS is leaking. You can try the test with and without the VPN connected and see the difference.
To test for a DNS leak, make sure you are connected to the VPN, then go to our DNS Leak Test page. Choose the thorough test and click Start Test.
After about 30 seconds, the results will be displayed.
Understanding the results
After the DNS Leak Test has completed, you will see your results, which will show the number of DNS servers that were queried and a list of their IP addresses, locations and service providers.
If you are connected to our VPN service and it is correctly configured, the results should only show one DNS server and the provider should be My Private Network. Note the IP address may differ from your VPN IP address as many of our servers use multiple addresses, however the Location and the Provider should always be the same.
If your DNS is leaking, then either the IP address will not be the same as the VPN, or you will see more than one DNS server in the results.
What causes a DNS Leak?
DNS Leaks are caused by either a configuration problem or your device / operating system not doing as it is told. For example, certain versions of Microsoft Windows will continue to query the local DNS servers even when the VPN is connected. With Apple's OSX, if you define a specific DNS server on your network connection, it will continue to use this even with the VPN connection.
There are simply too many causes of DNS Leaks for us to list them all here, but if you have a specific query, simply send us your test results and an overview of your setup and will be able to advise you on a course of action to stop the leak.
How does the test work?
Our DNS Leak Test instructs your web browser to query a series of unique internet names via your DNS settings. We can then see where those queries came from and then display the results back to you. The normal test generates 10 queries and the thorough test generates 30.
We are always here to help you, if you have any queries or would like more information, just drop us an email - firstname.lastname@example.org and we will get back to you as soon as possible.