How to test your device for this vulnerability

DNS Leak is a potential privacy threat that comes with using a VPN.

Speaking of DNS, we refer to that service that translates a hostname into an IP address and is used silently by any device connected to the internet (computer, telephone, game console, etc.).

Our devices ask a DNS server, typically that of our internet connection provider, for the destination IP to reach the resource (website, file to download or other servers).

1. What is DNS Leak

So far, it’s all normal because the whole internet relies on the use of DNS servers and you can’t do without them. The attack on our privacy occurs if, the internet service provider or another DNS server, keeps a history of the calls we make from the computer / telephone to resolve the addresses and keeps our IP – which identifies us – stored together with the site that we want to visit.

In summary, the scenario is this:

In this way, your every activity on the internet is potentially exposed; moreover, even an attacker in the middle can intercept the traffic since the DNS request is made completely in the clear and without encryption.

The term DNS Leak is used when the service provider or DNS server is able to know our movements on the internet, also in presence of a VPN connection that we use to protect our privacy and internet activity.

2. How to prevent DNS Leak

2.1 Use a secure VPN

VPNs are the modern, safest, and most reliable way to browse the internet and do any business while remaining anonymous. The main task of VPNs is to hide our IP address and encrypt the traffic that comes out of our devices through the tunnel.

However, not all VPNs are the same and equally secure. In fact, many VPNs are vulnerable to DNS Leak and you need to rely on certified VPNs that prevent DNS Leak.

We have had the opportunity to test many VNPs and try the goodness of each of them in our special on the Top VPNs of April 2021.

In short, the ones we recommend you use are the first in our ranking:

In addition to high security standards, these providers use the latest connection protocols and protect against DNS Leak.

2.2 Use DNS servers that protect privacy

You can, and indeed is highly recommended, use DNS servers other than those provided by your internet connection provider.

Setting up new DNS is an extremely easy operation that can be done on the router or on every single device you use. Read the in-depth study dedicated to changing DNS servers, valid for any Operating System.

The ones that we advise you to use and that claim to safeguard the user’s privacy are:

CloudFlare

1.1.1.1
1.0.0.1

Comodo Secure DNS

8.26.56.26
8.20.247.20

2.3 Use your own DNS server

A far from simple option is to set up and configure a new DNS server on our own. You need to subscribe to a VPS or a dedicated server, in a different country and configure the DNS server that we will use for address resolution.

We will not describe this solution in detail because it is very advanced and beyond the scope of the article, but it remains a possibility for the most savvy and experienced users.

3. DNS Leak Test: Check if you are vulnerable

A very simple method to check the DNS server used is to connect to your VPN and perform a command line DNS query with nslookup.

nslookup -q=A whoami.akamai.net

The address resulting from the DNS query, in order not to have leaks, must be that of the VPN.

C:Usersubik>nslookup -q=A whoami.akamai.net
Server: ubik-r9000
Address: 122.168.25.1