The Domain Name Server (DNS) is the Achilles heel of the Web. The important thing is that it's managed responsibly. -Tim Berners-Lee
Your DNS cache stores the locations of servers (webpages etc) that your computer has recently accessed.
The method for clearing this cache depends on your device.
Start by opening a command-window
Win + R - CMD
Run the following command and presto!
Ubuntu 17 >
sudo systemd-resolve --flush-caches
sudo /etc/init.d/nscd restart
sudo service dnsmasq restart