How to Flush DNS: A Step-by-Step Guide

How to Flush DNS: A Step-by-Step Guide

Introduction

The Domain Name System (DNS) is responsible for translating human-readable domain names (e.g., www.example.com) into IP addresses that computers use to identify each other on the network. Over time, your computer may cache DNS entries to speed up future requests. However, outdated or incorrect DNS records can cause issues like website loading errors, connectivity problems, or security vulnerabilities.

Flushing your DNS cache clears these stored records, forcing your system to fetch fresh DNS information from the DNS server. This article will guide you through the process of flushing DNS on various operating systems.

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Why Flush DNS?

  1. Resolve Connectivity Issues: If a website isn't loading properly, it could be due to an outdated DNS entry.
  2. Improve Security: Flushing DNS can help prevent DNS spoofing or cache poisoning attacks.
  3. Access Updated Websites: If a website has changed its IP address, flushing DNS ensures you're accessing the correct server.
  4. Troubleshoot Network Problems: Clearing the DNS cache can help resolve network-related issues.

How to Flush DNS on Different Operating Systems

1. Windows

Steps:

  1. Open Command Prompt as Administrator :

    • Press Windows + S and type "cmd".
    • Right-click on "Command Prompt" and select Run as administrator .

  2. Flush DNS :

    • In the command prompt, type the following command and press Enter:
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      ipconfig /flushdns

  3. Confirmation :

    • You should see a message saying:
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      Successfully flushed the DNS Resolver Cache.

  4. Exit :

    • Type exit and press Enter to close the command prompt.

2. macOS

For macOS versions Mojave (10.14) and later:

  1. Open Terminal :

    • Press Command + Space, type "Terminal", and press Enter.

  2. Flush DNS :

    • Enter the following command and press Enter:
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      sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
    • You may be prompted to enter your administrator password. Type it and press Enter.

  3. Confirmation :

    • There will be no visible confirmation in the terminal, but the DNS cache has been cleared.

For macOS versions Sierra (10.12) to High Sierra (10.13) :

  1. Open Terminal .
  2. Flush DNS :
    • Use the following command:
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      sudo killall -HUP mDNSResponder

3. Linux

DNS caching behavior depends on the distribution and whether a DNS caching service (like systemd-resolved, dnsmasq, or nscd) is running.

For systems using systemd-resolved (e.g., Ubuntu 18.04+):

  1. Open Terminal .

  2. Flush DNS :

    • Run the following command:
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      sudo systemd-resolve --flush-caches

  3. Check Status :

    • To verify the cache has been cleared, run:
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      systemd-resolve --statistics

For systems using nscd:

  1. Restart the DNS Cache Service :
    • Run the following command:
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      sudo systemctl restart nscd

For systems using dnsmasq:

  1. Restart the DNS Cache Service :
    • Run the following command:
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      sudo systemctl restart dnsmasq

4. Chrome OS

Chrome OS doesn't have a built-in way to flush DNS directly from the system. However, you can clear the DNS cache by restarting the device or using Chrome's internal settings:

  1. Open Chrome Browser .
  2. Navigate to Chrome's DNS Settings :
    • Type chrome://net-internals/#dns in the address bar and press Enter.
  3. Clear Host Cache :
    • Click the Clear host cache button.

5. Android

Android devices don't provide a direct way to flush DNS, but you can reset the network settings or toggle airplane mode to clear cached DNS entries.

Steps:

  1. Toggle Airplane Mode :

    • Turn on Airplane Mode for a few seconds, then turn it off.

  2. Reset Network Settings (Optional):

    • Go to Settings > System > Reset options > Reset Wi-Fi, mobile & Bluetooth .
    • Note: This will reset all saved Wi-Fi networks and Bluetooth connections.

6. iOS (iPhone/iPad)

Similar to Android, iOS doesn't offer a direct method to flush DNS. However, you can reset the network settings to clear DNS cache.

Steps:

  1. Go to Settings :
    • Navigate to Settings > General > Transfer or Reset iPhone .
  2. Reset Network Settings :
    • Tap Reset > Reset Network Settings .
    • Note: This will erase saved Wi-Fi passwords and reset network configurations.

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