How to Flush DNS: A Comprehensive Guide for Windows, macOS, and Linux

The Domain Name System (DNS) is the internet’s phonebook, translating human-readable domain names (like google.com) into IP addresses that computers use to communicate. When you visit a website, your computer first queries a DNS server to find the corresponding IP address. This information is often stored in your computer’s DNS cache to speed up future visits to the same site. However, sometimes this cached information becomes outdated or corrupt, leading to problems like websites not loading, error messages, or slow internet browsing. This is where flushing your DNS cache comes into play. By clearing the cache, you force your computer to fetch the latest DNS records, often resolving these connectivity issues.

This comprehensive guide will walk you through the process of flushing your DNS cache on various operating systems, including Windows, macOS, and Linux. We’ll also discuss why you might need to flush your DNS and the potential benefits it offers.

Why Flush Your DNS Cache?

Before we dive into the how-to, let’s understand why flushing your DNS cache can be beneficial:

• Website Loading Issues: If a website has recently changed its IP address, your cached DNS information might be outdated. This can prevent you from accessing the site or result in slow loading times. Flushing the DNS cache forces your computer to retrieve the new IP address.
• Error Messages: DNS errors, such as “DNS_PROBE_FINISHED_NXDOMAIN,” can often be resolved by clearing the cache. These errors usually indicate that your computer can’t find the correct IP address for a website.
• Security Concerns: In some rare cases, malware can manipulate your DNS cache, redirecting you to malicious websites. Flushing the cache can remove these corrupted entries.
• Network Changes: If your network configuration has been modified, such as switching DNS servers, flushing the DNS cache ensures that your computer uses the new settings.
• Testing DNS Changes: When making changes to your DNS records (e.g., changing web hosting providers) flushing your DNS cache ensures your changes are correctly picked up on your machine.
• Troubleshooting General Connectivity Problems: Flushing your DNS cache is often a go-to troubleshooting step when experiencing general internet connectivity issues.

How to Flush DNS on Windows

Flushing your DNS cache on Windows is straightforward. You can do this using the Command Prompt or PowerShell. Here are the step-by-step instructions:

Using Command Prompt

1. Open Command Prompt as Administrator:
   • Press the Windows key and type “cmd” or “command prompt”.
   • Right-click on the “Command Prompt” icon and select “Run as administrator”.
   • Click “Yes” if prompted by User Account Control (UAC).
2. Type the Flush DNS Command:
   • In the Command Prompt window, type the following command and press Enter:

   ipconfig /flushdns

3. Confirmation:
   • If the command is successful, you will see a confirmation message indicating that the DNS Resolver Cache was successfully flushed.
4. Close the Command Prompt:
   • You can now close the Command Prompt window.

Using PowerShell

1. Open PowerShell as Administrator:
   • Press the Windows key and type “powershell”.
   • Right-click on “Windows PowerShell” and select “Run as administrator”.
   • Click “Yes” if prompted by User Account Control (UAC).
2. Type the Flush DNS Command:
   • In the PowerShell window, type the following command and press Enter:

   Clear-DnsClientCache

3. Confirmation:
   • Unlike Command Prompt, PowerShell won’t show a direct confirmation message. However, if the command executes without errors, it means the DNS cache has been flushed.
4. Close PowerShell:
   • You can now close the PowerShell window.

How to Flush DNS on macOS

Flushing your DNS cache on macOS is also done through the Terminal. The command varies slightly depending on your macOS version. Here are the instructions for different versions:

macOS Ventura, Monterey, Big Sur, Catalina, and Later Versions

1. Open Terminal:
   • Go to “Applications” > “Utilities” > “Terminal”. Or, you can use Spotlight Search (Command + Space) and type “Terminal” then press Enter.
2. Type the Flush DNS Command:
   • In the Terminal window, type the following command and press Enter:

   sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

   • You will be prompted to enter your administrator password. Type your password and press Enter (note that your password will not be displayed as you type).
3. Confirmation:
   • The command doesn’t provide a confirmation message but if it completes without errors then the DNS cache is flushed.
4. Close Terminal:
   • You can now close the Terminal window.

macOS High Sierra, Sierra, El Capitan, Yosemite, and Earlier Versions

1. Open Terminal:
   • Go to “Applications” > “Utilities” > “Terminal”. Or, you can use Spotlight Search (Command + Space) and type “Terminal” then press Enter.
2. Type the Flush DNS Command:
   • In the Terminal window, type the following command and press Enter:

   sudo discoveryutil udnsflushcaches

   • You will be prompted to enter your administrator password. Type your password and press Enter (note that your password will not be displayed as you type).
3. Confirmation:
   • The command doesn’t provide a confirmation message but if it completes without errors then the DNS cache is flushed.
4. Close Terminal:
   • You can now close the Terminal window.

How to Flush DNS on Linux

Flushing your DNS cache on Linux can vary depending on the distribution you’re using. Most distributions use systemd-resolved or nscd for DNS resolution. Here’s how to flush DNS on common Linux systems:

Using systemd-resolved

Many modern Linux distributions, such as Ubuntu, Debian, Fedora, and Arch Linux, use systemd-resolved for DNS resolution.

1. Open Terminal:
   • Open your terminal application. You can usually find this in the applications menu or by pressing Ctrl + Alt + T.
2. Type the Flush DNS Command:
   • In the Terminal window, type the following command and press Enter:

   sudo systemd-resolve --flush-caches

   • You may be prompted to enter your administrator password. Type your password and press Enter (note that your password will not be displayed as you type).
3. Confirmation:
   • The command doesn’t usually display a confirmation message, but if it completes without errors, the DNS cache has been cleared.
4. Close Terminal:
   • You can now close the Terminal window.

Using nscd (Name Service Cache Daemon)

Some Linux distributions use nscd for DNS caching. Here’s how to flush the DNS cache in this case:

1. Open Terminal:
   • Open your terminal application. You can usually find this in the applications menu or by pressing Ctrl + Alt + T.
2. Type the Flush DNS Command:
   • In the Terminal window, type the following command and press Enter:

   sudo service nscd restart

   • Or you can try:

   sudo /etc/init.d/nscd restart

   • You may be prompted to enter your administrator password. Type your password and press Enter (note that your password will not be displayed as you type).
3. Confirmation:
   • The command will restart the nscd service and flush the DNS cache. The output might vary depending on your Linux distribution.
4. Close Terminal:
   • You can now close the Terminal window.

Using dnsmasq

If you are using dnsmasq as a local DNS forwarder then use the following command:

1. Open Terminal:
   • Open your terminal application. You can usually find this in the applications menu or by pressing Ctrl + Alt + T.
2. Type the Flush DNS Command:
   • In the Terminal window, type the following command and press Enter:

   sudo service dnsmasq restart

   • Or you can try:

   sudo /etc/init.d/dnsmasq restart

   • You may be prompted to enter your administrator password. Type your password and press Enter (note that your password will not be displayed as you type).
3. Confirmation:
   • The command will restart the dnsmasq service and flush the DNS cache. The output might vary depending on your Linux distribution.
4. Close Terminal:
   • You can now close the Terminal window.

After Flushing Your DNS Cache

After flushing your DNS cache, it’s a good idea to restart your web browser and any network-dependent applications. This ensures that the applications use the newly retrieved DNS information.

Important Note: Flushing your DNS cache only affects your local machine. Other devices on your network will still have their own cached DNS records. Also, if the root cause of the problem is with your network equipment, or your DNS servers, flushing your local DNS cache may not resolve the problem.

Troubleshooting Further Issues

If flushing the DNS cache does not solve your problems, the issues might lie elsewhere. Here are some next steps you can take:

• Restart Your Modem/Router: Power cycle your network equipment to refresh the network connection.
• Change DNS Servers: Try using public DNS servers like Google Public DNS (8.8.8.8 and 8.8.4.4) or Cloudflare DNS (1.1.1.1 and 1.0.0.1).
• Check Your Firewall: Your firewall might be blocking DNS communication. Adjust firewall settings accordingly.
• Examine Your Hosts File: In rare cases, your hosts file may be redirecting requests to incorrect IPs. Make sure there are no unexpected entries.
• Check Your Antivirus Software: Sometimes overly-aggressive antivirus programs can interfere with your network connection. Temporarily disable it to test if it’s the issue.

Conclusion

Flushing your DNS cache is a simple yet effective troubleshooting step that can often resolve a variety of network issues. By following the steps outlined in this guide, you should be able to clear your DNS cache easily on Windows, macOS, and Linux. Remember to restart your browser and other applications after flushing the cache to ensure your changes take effect. If you still encounter problems, explore the troubleshooting steps above or consult with a network expert. Understanding your computer’s DNS cache and how to manage it is a fundamental part of ensuring smooth online browsing.