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DNS cache poisoning and how to protect yourself against this threat

In our “always-connected” world, the Internet is critical in our daily life. It is therefore important to implement efficient solutions to protect the Domain Name System (DNS), one of the key elements allowing you to access your favourite websites and exchange emails. Also known as DNS spoofing, DNS poisoning one of the DNS attack that absolutely has to be taken into consideration.

DNS cache poisoning: short definition and main consequences


The function of the DNS server is to convert alphabetic names into IP addresses– every internet research that you do rely on the DNS protocol, one of the oldest protocols of the internet. There has been a long history of attacks on the DNS, and one of the most commons is called DNS cache poisoning.


In DNS cache poisoning, the hacker tries to get the caching server accept false information. If he succeeds, this fake answer is in replacement of the “real” one and the pirate server becomes the authoritative one. The attacker must be skilled, because his fake response must perfectly match the query parameters of the actual “true” response.


DNS cache poisoning is one of the most prominent and dangerous attacks on DNS, since once the cache has been poisoned with false information, any information requested will then be answered with this poisoned answer. The danger is that users usually do not even realise that they became the target of such an attack. As a consequence, they still divulge personal data on what they believe to be the “official” website. The user accesses the malicious site (such attacks are called pharming); these fake websites contain tools for stealing information or infecting computers.

DNS cache poisoning


Fortunately, there exist solutions that can monitor the DNS server and detect any abnormal request. Perhaps it is time for your business to adopt a powerful solution that can protect you against DNS cache poisoning; especially if your business provides online services and has to deal with private information.

Some advice to thwart DNS cache poisoning attacks

The DNS is prone to certain weaknesses, and here are some advice to prevent your system from being hacked:


  • First of all, you should keep your resolver private and protected and restrict its usage to familiar users- in short, never open it to external users.
  • Manage your DNS server securely. You absolutely need to choose whether you prefer to host your servers yourself, or to have them hosted. Moreover, you always have to keep your servers up-to-date and patched if you to prevent your system from becoming vulnerable.
  • Configure your system against cache poisoning; by regularly monitoring DNS requests and blocking illegitimate ones, you will decrease the risk of becoming the victim of DNS cache poisoning.

There are many protocols that enable you to use the Internet properly. DNS is one of those, and it is critical to its proper functioning. Adopting better network practices and providing your system with the proper layer of defense will inevitably help you avoid DNS attacks, such as DNS cache poisoning.