DNS Leaks (22/53 VPNs Leak Your Data)

To start with, let’s dig into the meaning of DNS – Domain Name Service

According to Stanford University, DNS is the network service that maps Internet domain names to numerical IP addresses.

Seems easy right?

To bring an analogy, it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses.

For example: www.example.com translates to the addresses (IPv4) and 2606:2800:220:1:248:1893:25c8:1946 (IPv6)

Historically, Stanford Research Institute (now SRI International) handled database of all the simplified domain names by hand.

To request a hostname and an address and add a computer to the master file, users had to contact the SRI.

Could you imagine in?

The Internet grew so rapidly that they just couldn’t keep up with it and finally made it automated.

Now we have separate organisations who do that for every website. For example:

  • Google Cloud DNS
  • EasyDNS
  • Amazon Route 53

Interesting, right!

Coming back to the DNS leaks. How they happen and why should you care?

DNS Leak

Every time you connect to a website, your signal goes trough a process.

Users don’t usually communicate directly with DNS resolvers, we need a client programs for that – Your web browser.


Your web browser sees the IP address your device uses (a fingerprint) and requests DNS search trough your ISP (Internet Service Provider).

With a VPN, your device asks VPN server for DNS service instead.

To sum it up,

when VPN is not stable or fails to work due to technical error, your machine with real IP is asking your ISP for DNS and this unwanted situation is called DNS leak.

Which VPNs Leak DNS? (Case Study with 53 VPNs)

To answer this question, we subscribed and installed 53 most popular VPNs to our lab laptop.

We tested them with 5 different leak detecting service and recorded the results.

The tests were quite stunning.

Slightly less than half of the service providers leak your data!

Total threat count

So which VPNs leak?

List of tested VPNs (A-Z):

  • AirVPN (0)
  • Astrill VPN (0)
  • Avast Secureline (0)
  • Avira Phantom VPN (0)
  • Betternet VPN (0)
  • Browsec VPN (0)
  • Buffered VPN (0)
  • Cryptic VPN (5)
  • CyberGhost VPN (0)
  • EarthVPN (4)
  • ExpressVPN (0)
  • FastestVPN (5)
  • Fly VPN (4)
  • Freedome VPN (0)
  • Ghostpath VPN (0)
  • Hide.me (0)
  • HideMyAss VPN (4)
  • Hola VPN (5)
  • HotSpotShield (0)
  • IbVPN (4)
  • IPVanish VPN (0)
  • Ivacy VPN (5)
  • Le VPN (0)
  • Lime VPN (4)
  • NordVPN (0)
  • Norton VPN (0)
  • OneVPN (5)
  • Overplay VPN (0)
  • Perfect-Privacy (0)
  • PIA (0)
  • ProtonVPN (0)
  • Psiphon VPN (1)
  • Pure VPN (0)
  • Seed4.me (0)
  • Shadeyou (0)
  • SmartVPN (5)
  • Steganos VPN (0)
  • Strong VPN (0)
  • Sumrando (5)
  • Zenmate VPN (4)
  • Tiger VPN (0)
  • TorGuard (0)
  • Trust Zone VPN (4)
  • TunnelBear VPN (5)
  • Ultrasurf VPN (1)
  • WindScribe VPN (0)
  • VPN Gate (4)
  • VPN Unlimited (4)
  • VPN.asia (5)
  • vpn.ht (5)
  • VPNinja (5)
  • VPNSecure Me (0)
  • VyprVPN (0)

(number count corresponds to how many leak sites it failed)

Your VPN wasn’t listed?

Not a problem, you can make your own tests.

Test Your VPN for DNS Leaks:


DNS Leak is Not the Only Threat

Remember when Edward Snowden shocked the world by commenting smartphone backdoors?

Even VPNs might have it!

A good way to start is to check for any viruses, this could be done easily with online tools.


How to Protect Yourself From DNS Leak? (6 Tips)

The good news is, there are safety measure to protect yourself from DNS leaks.


Here is a list of things to do:

  1. Use a good VPN.
  2. Just in case, test your VPN before using. Check the tools available above.
  3. Use VPNs with kill-switch and turn it “ON”.
  4. Use Tor
  5. Change your default DNS server
  6. Disable Teredo (using Windows, go to command prompt and type “netsh interface teredo set state disabled”.


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