Most computers that are connected to the internet automatically cache
the hostname of the websites you have visited to make reloading the
pages faster than if there was no cache. If the IP address of a website
changes before your cache updates, you may not be able to load the
webpage. If you are running into a lot of “Page Not Found” errors and
you know you’re connected to the internet, try flushing your DNS cache
to have your computer request new information.
The link below will take you to a page which will show you how to flush your DNS cache: