Interested in flushing your Ubuntu DNS cache? Note: I’m running Jaunty Jackalope as of the date of this post.
Well, Ubuntu doesn’t cache DNS by default. Your cache rests within your router, or your assigned DNS servers. You could restart your router, if you have access to it. Or wait until the time-to-live has expired.
You can install a local resolver that will cache DNS addresses, if you like. It will speed up your Web access slightly, since your Web browser will check the local cache first. I imagine the time you save will be measured in milliseconds.
Do that with:
sudo apt-get update && sudo apt-get install nscd
And to clear your local cache, restart the service:
sudo /etc/init.d/nscd restart