DNS leaks. The idea behind VPNs is that they create encrypted tunnels between the client on your computer or mobile device and the VPN server, where data is decrypted before it travels to its destination, such as a website.

For internet users, VPN means extra security to encrypt data, hide IP addresses, protect anonymity and privacy, surf the internet freely and safely, and use public Wi-Fi. However, regardless of the purpose of choosing the VPN service, a VPN leak can prevent all this and cause serious dangers.

People often feel more comfortable engaging in risky online activities when they think their VPN is protecting them. If a VPN leaks without the user’s knowledge, it can result in a serious problem.

Due to security vulnerabilities, personal data can sometimes leak into the network. When things don’t go the way they should, a VPN leak and exposed data allow interceptors to associate your activity with your identity.

If that happens, anyone spying on you can actually find out what you’re doing, and all the effort of using a VPN will go to waste. If your VPN is leaking, you could be just as vulnerable as someone who isn’t using it. That’s why it’s so important to be aware of VPN leaks and learn how to avoid them.

Of the different types of leaks, the most important are:

• DNS (Domain Name) Leak
• IP (Internet Protocol Address) Leak
• WebRTC (Web Real-Time Communication) Leak

DNS (Domain Name) Leak

DNS leaks occur when DNS requests go to the Internet Service Provider (ISP) instead of the VPN provider. DNS is a directory that translates domain names into IP addresses. Under normal circumstances, when you want to visit a website, your device sends a DNS query to the DNS server, which converts the URL to the site’s numeric IP address.

The whole process basically just translates things in our language into machine language. Using a VPN should make the DNS request go to the VPN provider. So your ISP can’t find out what you’re doing. If your VPN isn’t working properly and the DNS request is going to your ISP, it makes the site you’re visiting open to both your ISP and anyone else spying on you.

DNS leaks can be very dangerous if you are doing something that requires absolute confidentiality. DNS leaks can be checked with DNS leak testing.

IP (Internet Protocol Address) Leak

IP is the address of the router used to establish the internet connection. When connecting to a website, site administrators, your ISP, and anyone watching you can see your router’s IP address. Obviously, this is not a good situation. When a VPN is working properly, the ISP can see connecting to a VPN server, but then not the traffic.

On the other side of the VPN, the site administrator will see the data from the VPN exit server, but will not be able to determine the IP address from where the data is coming from. This setup prevents your IP address from being exposed. There are two different IPs:

• IPv4 
• IPv6 

IPv4 has been used since the eighties and IPv6 is a newer version that became standard in 2017. It can be checked whether you are using IPv4 or IPv6 online. If you have IPv6 and your IP address is leaking from your VPN, it may be possible to fix the problem without having to change providers.

With the online IP leak test, you can find out if there is an IP leak. For Windows or Mac OSX, you can disable IPv6 and revert to IPv4. Common IP leaks include:

• Traffic Leaks
• Persistent and Triggered Leaks

Traffic Leaks

Traffic leaks are the worst types of leaks and leak all of your traffic outside the VPN tunnel. If you have a traffic leak, your ISP and anyone spying on you can see all your data. Traffic leaks can often occur when the connection is lost. That’s why it’s important to choose a VPN provider with a Kill Switch feature.

If the VPN connection is lost, the Kill Switch will kick in and disconnect your connection. If your VPN does not have a Kill Switch and the connection drops, your internet connection may continue and all your traffic will be exposed.

Persistent and Triggered Leaks

These leaks come in three main forms:

1. Persistent Pre-Existing Leaks
2. Triggered Persistent Leaks
3. Temporary Triggered Leaks

Persistent Pre-Existing Leaks

Pre-existing persistent leaks can be caused by problems with the VPN or its configuration. If you have one of these, some of your data will always be leaked.

Triggered Persistent Leaks

These leaks are triggered by certain events, such as your internet connection dropping or VPN crashing. Once the trigger occurs, the VPN will continue to leak data until the issue is fixed. If the event has happened before, these leaks will easily show up in tests.

Temporary Triggered Leaks

After certain outage events, temporarily triggered leaks occur, but data leaks only temporarily. These are the hardest to detect. Because users may never realize that their VPN is prone to leaks under certain circumstances.

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