How can I clear (flush) my DNS cache in Linux?

The Domain Name System (DNS) translates user-friendly domain names into the numerical IP addresses that computers understand. This translation process is expedited by the DNS cache, a local repository storing recent domain name lookups. While this cache enhances online efficiency, there are instances when its clearance becomes necessary. So, today, we will explain what it is and how to flush it in Linux systems and guide you through the process.

What is DNS Cache?

The Domain Name System (DNS) is a fundamental component of the internet, responsible for translating human-readable domain names into IP addresses that computers use to locate and communicate with each other. To expedite this process and reduce the time it takes to access websites or other online resources, operating systems and web browsers often maintain a local DNS cache.

In simple terms, a DNS cache stores recent DNS lookups, including the corresponding IP addresses. This means that when you visit a website, your computer doesn’t need to perform a full DNS lookup every time, which can improve page loading times. Instead, it can quickly retrieve the IP address from the cache. However, there are times when you might want to clear or flush it.

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​Linux, the object of the DNS cache poisoning attack

In 2020, researchers from the University of California and Tsinghua University found a new method to execute DNS cache poisoning attacks. Unfortunately, Linux, a very reliable OS, was the object of the DNS cache poisoning attack.

What is DNS cache poisoning?

A DNS cache poisoning (DNS spoofing) is a cyberattack that pollutes the cache on DNS resolver servers. This can cause the user to be redirected to the attacker’s server instead of the right one.

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