Why does DNS cache matter & How to flush it?

Data exchange happens at a lightning pace. Every time you type a website address into your browser, it doesn’t immediately connect you to the requested website. Instead, a series of behind-the-scenes processes take place, one of which involves DNS (Domain Name System) resolution. DNS acts like a directory, translating human-readable domain names into IP addresses that computers can understand. But what role does DNS cache play in this process, why does it matter, and how can you flush it when necessary?

What is DNS Cache?

DNS cache is a mechanism employed by computers and networking devices to store recently accessed DNS information locally. When you visit a website for the first time, your computer sends a request to a DNS resolver to translate the domain name into an IP address. Once the resolver obtains the IP address, it stores it in its cache for future use. Next visits to the same website skip the DNS resolution process and directly access the IP address from the cache, speeding up the browsing experience.

Why Does DNS Cache Matter?

The DNS cache plays a crucial role in speeding up internet access and reducing network traffic. Instead of repeatedly querying DNS servers for the IP addresses of frequently visited websites, the cache provides quick access to this information locally. This results in faster load times for websites and improved overall browsing efficiency.

Moreover, the DNS cache also enhances network reliability. In situations where DNS servers experience downtime or network congestion, cached DNS records enable continued access to websites whose IP addresses are stored locally. This redundancy ensures that users can still reach their desired destinations even under adverse network conditions.

How to Flush DNS Cache?

Despite its benefits, there are times when you might need to flush or clear the DNS cache. This could be due to various reasons such as troubleshooting network connectivity issues, ensuring that you’re accessing the most updated versions of websites, or removing outdated or incorrect DNS records.

Here’s how you can flush it on different operating systems:


  1. Press the Windows key and type “Command Prompt” in the search bar.
  2. Right-click on Command Prompt and select “Run as administrator.”
  3. In the Command Prompt window, type the following command and press Enter: ipconfig /flushdns 


  1. Open the Terminal application. You can find it in the Applications folder under Utilities, or simply search for it using Spotlight.
  2. In the Terminal window, type the following command and press Enter: sudo killall -HUP mDNSResponder 


  1. Open a terminal window.
  2. Depending on your Linux distribution, use one of the following commands:
  • For systemd-resolved systems: sudo systemd-resolve –flush-caches 
  • For systems using nscd (Name Service Cache Daemon): sudo /etc/init.d/nscd restart 
  • For systems using dnsmasq: sudo /etc/init.d/dnsmasq restart 
  • For systems using BIND (Berkeley Internet Name Domain): sudo rndc restart 


DNS cache is a vital component of the internet infrastructure, contributing to faster website loading times and enhanced network reliability. While it generally operates seamlessly in the background, knowing how to flush it can be valuable for troubleshooting purposes or ensuring up-to-date DNS information. By understanding its role and how to manage it, users can optimize their internet experience and address connectivity issues effectively.

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