What is DNS Flushing?

Hello folks, today I thought I would explain what a DNS flushisng/FlushDNS is.

The reasoning behind this is that it's a common troubleshooting tool for when you may be experiencing some various connectivity issues. DNS resolution errors at the router level are common and if you're not aware of what a DNS flush is, you may be wasting time trying to troubleshoot an issue that's fixable via a quick DNS Flush.

Your Domain Name System (DNS) reads websites like www.fing.com and translates them on their end into a form of IP addresses. Your DNS then keeps a cache, similar to how cache and cookies work on your browser, to save time the next time you go to access that site. Of course this can become outdated, and if you've reached out to IT support before you'll know that clearing your cache is one of the first troubleshooting tips you'll receive.

Clearing the cache on a semi-regular basis also removes the potential for 'tracking data' and can potentially protect you against the likes of DNS Poisoning (where hackers fake address records to send you to dangerous fake websites).

So, if you're running Fing Desktop and you see you're getting the warnings 'No DNS server is configured' or 'Unable to reach local DNS' – Fing is letting you know there's some DNS issues being experienced, and it's definitely worth trying a flushdns;

1. Turn off both your router and modem.
2. While they are off, clear your internet cache from all browsers, and close all browsers.
3. For Windows;
   • Go to command prompt (cmd) and run ipconfig /flushdns.
4. For MacOS: Open terminal
   • macOS Big Sur and newer: sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
   • macOS Catalina and older: sudo killall -HUP mDNSResponder

As a bonus, you can also;

On Windows;

1. Run ipconfig /release.
2. Run ipconfig /renew.

On MacOS;

• Open System Settings (or System Preferences on older versions).
• Click on Network in the sidebar.
• Select your active connection (like Wi-Fi or Ethernet).
• Click Details… next to your connection.
• Select the TCP/IP tab.
• Click Renew DHCP Lease, then click OK

This will drop your computer's current IP address assigned by your router and then renew will get it a new one.