How to clear the DNS cache with Terminal in macOS

To clear DNS cache on macOS systems, follow the steps below.

To flush the local DNS cache on macOS Catalina, follow the following steps.

Open Terminal (Application › Utilities › Terminal or press CMD+SPACEBAR and Type in ‘Terminal’ then select the black Terminal app in the list)
When Terminal Starts type: ‘sudo killall -HUP mDNSResponder’ and press Enter to run the command.
Enter your password (the password usually doesn’t show in Terminal but press enter when you’ve entered the password) which is required because you ran the command using ‘sudo ‘
Press Enter. Close the Terminal.
That’s it! Your local DNS cache in macOS Catalina should have been cleared!