Flush DNS

Modern browsers, OS, and DNS clients store cache of IP addresses and other DNS information automatically. When a computer visits a website for the first time, it stores the website's DNS information in the cache, and on the next visit of the same website, it looks in the cache to see if the web site's information is present to use. 

An old version of a site opens if the website's DNS information has changed since the computer's last visit.

Flushing the cache removes all the data stored in the cache, forcing the computer to find the new DNS information for the website. It is usually done to speed up the process and minimize requests for the same hostnames. When IP addresses are changed, or bad results are cached, its necessary to clear the DNS cache. DNS cache can be cleared via command line or from browsers also. Steps to flush DNS Cache for major operating systems and browsers are as below.


Here is another one, check out both for an explanation and find the tool best for you.