DNS settings may be something that you don’t need to consider very often, but if you have opted to use servers other than those suggested by your ISP, or have some other need to change the server you’re using, you may find it useful to flush the cache. This clears out any settings that are out of date so that you will always visit the site — and version of the sites — you expect to see.
In addition to this the DNS cache can reveal a great deal of information about your online activity, so from a privacy point of view you may want to consider clearing it from time to time.
Press the Windows key and R at the same time to display the Run dialog. Type cmd and press Enter to bring up the Command Prompt.
At the Command Prompt, type ipconfig /flushdns and press Enter
You should see a message that reads Successfully flushed the DNS Resolver Cache.
You can then close the Command Prompt window.
Flushing the DNS cache may not be something you need to do all that often, but it’s a handy troubleshooting tips to have on hand for when the need arises.