This tutorial will help you to disable local DNS caching on Ubuntu and LinuxMint systems. You can also clear current DNS cache instead of disable it completely.

Disable DNS Cache

Log in to your system with the user has sudo privileges and Edit NetworkManager configuration file in your favorite text editor. Now comment the following entry by added # symbol to start of line like below.

Save the configuration file. Vi users use ESC + :wq to save file and quit. Execute below command to NetworkManager apply new settings. All done.

How to Disable Local DNS Caching on Ubuntu and LinuxMint   TecAdmin - 92