DNS Leak Test

DNS Server Leak Test: Which DNS does your device use?

After a short moment, you can see the DNS servers you are currently using. These were determined by a query from your browser. The information on the DNS servers may not be complete, for example, if you use Google DNS or Cloudflare DNS, then changing DNS addresses can be detected here, as these services use many servers in parallel to provide you with the free DNS service.

With the DNS Leak Test developed by us, everyone can find out more quickly which DNS their device is currently using. 

DNS Leak Test

Starte DNS Test


Our test of the DNS servers used tries to find out all DNS services, which is why we use special multiple queries here to provide accurate results. Therefore, it can sometimes take up to a minute before a result is displayed.

DNS leaks are a big problem

DNS leaks are an urgent security problem that should be of interest to everyone who uses the internet. Far too often, DNS queries make users completely transparent to their Internet service provider, the never-ending data retention also addresses exactly this vulnerability of users, and it is well known that the NSA runs mass surveillance programmes by monitoring DNS servers worldwide. Therefore, everyone should take an interest in which DNS servers they use and ensure that they only use secure DNS queries.

Institutional monitoring of DNS queries is one of the biggest security problems for data about a person’s or organisation’s activities on the Internet!
(Martin from VPNTESTER)

The entire “VPN Leak Test” is also available on our site here.

What is a DNS leak?

Our test shows you which DNS are leaked. Unwanted DNS servers represent a major security risk and official monitoring is also carried out via DNS servers (data retention), and websites are also made inaccessible to users via DNS blocks. It is, therefore, worthwhile to deal with this topic. 

What is DNS?

Domain name servers are services that inform the device of the IP address of a domain, for example, the IP address of the page zdf.de. This is required because all connections on the Internet are based on IP addresses.

What is a leak?

A leak is an information that leaks out or becomes known without the originator perhaps being aware of it. A DNS leak, therefore, refers to the DNS servers used by a device that may be unknown to the user.

What is a DNS test?

A DNS server test is used to find out which DNS a device is using at any given time. 

DNS server test explanation

Our test checks the DNS servers used via multiple queries directly from your browser – you may see several or even other DNS servers if you repeat the test several times. This is because many DNS server services also have links to other DNS servers. Therefore, each test query is only a snapshot and by no means complete. 

Caution with unwanted DNS server use

If the DNS servers you use seem unfamiliar to you and are used unintentionally, they can pose a security risk, as the DNS servers could also log all your activities or even manipulate them. 

Trojans are installed by manipulated DNS servers

Trojans such as those used by the authorities can be installed on a device via DNS servers of the internet provider, for example. In the process, conventional page requests are redirected and malware or Trojans are installed unnoticed by the user.



DNS with protocoling!
DNS with protocoling!



Our general DNS privacy considerations

The domain name system (DNS) is used for every website visit and email transmission, so privacy is an obvious concern.

In DNS, users ask recursive resolvers (or “recursive”) to make requests on their behalf. Previous analyses of DNS privacy have focused on privacy risks to individual end-users, particularly traffic between users and recursive. Recursive store and aggregate traffic for many users, factors that are generally assumed to protect end-user privacy over recursive.

We document institutional privacy (protection from surveillance by ISPs or global data services) as a new risk posed by DNS data collected on authoritative servers, even after caching and aggregation by DNS recursive.

Many experts like us identify this risk by looking at leaks in email traffic that reveal communication patterns, and leaks in access to sensitive websites, both of which can damage an institution’s public image. We define a method for identifying queries of institutions and detecting leaks.

We also aim to show that current practices of prefix-preserving anonymisation of IP addresses and aggregation above recursion are insufficient to protect the privacy of institutions, pointing to the need for new approaches. We demonstrate this claim by applying our methodology to real traffic from DNS servers that use partial prefix-preserving anonymisation. Our work leads to additional privacy considerations for institutions that operate their resolvers and for operators of authoritative servers that log and share DNS data.

Our DNS test results differ considerably from other tests that can be found on the internet. For questions about this and also if you need help, we are available on Telegram.

Frequently asked questions and explanations about DNS servers

I see DNS, do I have a DNS leak now?

Every device uses DNS servers to convert the names, for example zdf.de, into IP addresses. Therefore, the fact that you recognise DNS servers here is not yet a leak. It would be a problem if you only wanted to use specific DNS servers, for example those of your VPN service, and then found other DNS servers here. That would be a security problem.

What does a DNS server know about me?

A DNS server can generally recognise at least the IP address that you are currently using and the page that your device is requesting. This also means that almost all activities that you now carry out on the Internet can be traced via it.

DNS with protocoling!
DNS with protocoling!

Some VPN services therefore also offer their DNS servers for use to ensure that no data can be passed on to third parties that could provide information about a user’s surfing behaviour.

What is a DNA leak?

A “DNS leak” is when you use a DNS that records data about your surfing behaviour. In particular, it is a personal security risk if one has not consciously chosen this DNS server. DNS servers can recognise and record the entire usage behaviour of an Internet user. DNS servers can also be manipulated to carry out Trojans or other harmful activities.

Therefore, you should always be able to trust the DNS servers you use 100%.

Test your IP address

With another test, you can also find out more data about the IP address you are using.

My IP Address



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