A Mozilla Firefox add-on that provides a easy way to reload the browser DNS cache.
It's commonly used by developers that uses the Hosts File to force a domain name resolution to a specific IP.
DNS Flusher is a very simple tool for firefox (Addon/Extension) used to force refreshing it's DNS internal cache.
Install it via Mozilla Add-ons site or via Firefox Add-on manager
You have 2 options to access the plugin:
You'll see an icon (three arrows) next to an IP or a 'DNS Flusher' text on the bottom of the browser;
It's installed by the first time you add the Add-on to your browser;