DNS Leak setup guide

The Domain Name System (DNS) works as your Internet's directory that translates user-friendly domain names into numerical IP addresses that computers use to communicate.

When you enter a web address, your device queries a DNS server to find the IP address, and this facilitates the connection.​

Virtual Private Networks (VPNs) enhance your privacy as they route your internet traffic through encrypted tunnels to private servers. This keeps your IP address and data transfers hidden.

However, if your DNS requests bypass the encrypted tunnel and use an Internet Service Provider (ISP) instead, a DNS leak occurs. This reveals your browsing activity to your ISP or other third parties. It undermines the very purpose of using a VPN.​

What Is a DNS Leak?

A DNS leak occurs when the DNS queries transmit outside the secure VPN tunnel, when they reach your ISP's DNS servers. This occurs due to several reasons:​

VPN Misconfigurations: Incorrect VPN setup results in DNS requests not being routed through the VPN.

System or Browser Settings: Certain operating systems or browsers may default to using the ISP's DNS servers, even when a VPN is active.​

IPv6 or Smart DNS Interference: If a VPN doesn't support IPv6, DNS requests over IPv6 can leak. Also, smart DNS services overcome your VPN settings.​

Transparent DNS Proxies: Some ISPs use transparent proxies that mingle with DNS queries. This lets them through the ISP's DNS servers.

What Harm DNS Leaks Do?

It exposes your browsing activity, and your ISP can monitor and log the websites you visit.​ It bypasses VPN protection. The anonymity provided by the VPN is compromised.​ 

There's a risk of Man-in-the-Middle (MITM) Attacks. Attackers can manipulate your DNS queries.​ Malicious entities can redirect your traffic to fraudulent websites or track your online behavior.​

Why is a DNS Leak Check Needed?

DNS is important for security and privacy.

Privacy: Ensures your DNS requests remain confidential and aren't exposed to unauthorized parties.​

Security: Prevents potential interception or manipulation of your DNS traffic.​

Compliance: Adhere to data protection regulations, especially in sectors like finance and healthcare.​

VPN Testing: Verifies that your VPN is correctly configured and functioning as intended.​

Leaked DNS queries can inadvertently reveal sensitive information about the websites you access. It has real-world risks to your privacy and security.​

How to Check for a DNS Leak Manually?

First, disconnect from your VPN and note your current IP address and DNS server.​ Next, reconnect to the VPN and use an online DNS leak test tool.

Now compare the displayed IP and DNS server addresses with those noted earlier. If they match, a DNS leak is present.​

Tools You Can Choose for Checking DNS Leaks:

Browser-Based Tools: Websites that analyze your DNS requests to identify leaks.​

Network Diagnostic Tools: You can use utilities like “dnsleaktest” can help detect leaks.​

OS-Level Tools: Advanced users can employ commands like nslookup, dig, or packet analyzers like Wireshark for in-depth analysis.​

How DNS Leaks Occur?

Common situations that lead to DNS leaks include:

Using a VPN Without IPv6 Support: DNS requests over IPv6 may leak if the VPN doesn't handle IPv6 traffic.​

Improper Split Tunneling Configuration: Incorrect settings can route some traffic outside the VPN tunnel.

WebRTC-Enabled Browsers: Browsers that have WebRTC can expose your real IP address and lead to DNS leaks.​

Default System DNS Settings: Operating systems may revert to using the ISP's DNS servers.​

VPNs Lack DNS Leak Protection: Not all VPNs offer you built-in mechanisms to prevent DNS leaks.​ 

How To Prevent DNS Leaks?

To protect your data against DNS leaks, you can do the following:

Go with a VPN with DNS Leak Protection: Always opt for VPN services that offer you built-in DNS leak protection and use their own DNS servers.

Manually Configure your DNS Servers: Set your device to use trusted DNS servers, such as those provided by your VPN or reputable public DNS services.​

Disable WebRTC in Your Browser: This helps you prevent IP leaks by turning off WebRTC functionality.​

Implement Firewall Rules: Configure your firewall to block any traffic that doesn't go through the VPN.​

Verify DNS Settings After Connecting to VPN: Regularly check that your DNS requests are routed through the VPN's DNS servers.​

Use Encrypted DNS Protocols: Employ DNS over HTTPS (DoH) or DNS over TLS (DoT) for enhanced security.​

DNS Leak vs. IP Leak 

DNS Leak occurs when your DNS queries go outside the VPN tunnel and expose the websites you visit. IP Leak happens when your actual IP address is revealed despite using a VPN.

Even if your actual IP address remains hidden, the queries can still reveal every site you visit.

On the other hand, an IP leak happens when your real IP address becomes visible to websites or third parties. This way it defeats the core function of a VPN. This happens due to misconfigured VPNs, browser vulnerabilities (like WebRTC), or poor VPN service.

A DNS leak reveals what you're accessing, while an IP leak reveals who is accessing it. Both are dangerous and you need to check and prevent them regularly to maintain powerful digital privacy.

FAQs

What is a DNS leak in simple terms? A DNS leak happens when your device sends website lookup requests (DNS queries) outside your secure VPN connection.

How to know if I have a DNS leak? You can check by using an online DNS leak testing tool after you connect to your VPN. If your ISP’s DNS server is in the results, you have a leak.

Can a DNS leak expose my identity? Yes. It surely will not reveal your name. It exposes the websites you visit.

Can free VPNs protect against DNS leaks? Not always. Many free VPNs have no features like DNS leak protection. So it’s better to have a good paid service that offers it.

Can there be DNS leaks even if my IP is hidden? Yes. If your IP is masked by a VPN. DNS requests still go through your ISP, and your browsing history gets exposed.

Conclusion

When you use a VPN, you take an important step to protect your online privacy, but it isn’t risk-free.

A DNS leak can silently expose your web activity to ISPs, corporations, or even malicious actors, and you won’t even know. Regular DNS leak checks help you verify that your VPN actually routes your DNS traffic through encrypted channels.

Preventing DNS leaks needs a reliable VPN with built-in protection, and you also need to manually configure secure DNS servers, disable WebRTC, and stay proactive with routine checks.

If online privacy matters to you for your personal safety, compliance, or peace of mind, then you need to have good know-how about DNS leaks.