How to Flush the DNS Cache

Domain Name Server (DNS) names are the IP (Internet Protocol) addresses of the servers that have a very large repository of practically all the internet addresses inside their vaults. These servers handle the job of translating the normal plain English Universal Resource Locators (URL’s) into their IP addresses so that the browser can understand and connect to the website. Basically envisioned and implemented by the Internet Engineering Task Force (IETF) as a large cache of URL so that the name server can understand, verify and resolve domain names speedily.

The DNS information of every visit to a website is stored in a cache of the computer that navigates to a specific website. On recurring visits, the browser will first look up the computer’s own repository before calling on the DNS with the information on the domain. If it gets a match before calling the DNS, then it works with just this information and will not forcefully ask the DNS for server information. This cache is stored for up to twenty four hours (depending on the system’s configuration). This enhances the speed with which the browser redraws and renders a website from its internet servers. However when the website changes its IP address within this twenty four hour period then the browser will not display the website as it does not look up the IP information from the Domain Name Servers. As it is very hard to delete a specific entry, and there is no way to override the system configuration in this regard, the only way to get rid of false entries is by flushing the DNS cache.

To flush the DNS cache in Microsoft’s Windows NT, 2000 and later editions, the steps to be followed are:

• Click on the Start Button and click on the Run button.
• Type ‘Command’ or ‘cmd’ to get into the command prompt.
• Type ipconfig/flushdns to flush the DNS cache.

If the flush was successful, the command line interface should display these messages:

“Windows IP Configuration
Successfully flushed the DNS Resolver cache.”

If however, you wish to stop the caching of addresses permanently (in the light of repeated negative entries) you can type ‘net stop dnscache’ or ‘sc server stop dnscache’ to permanently stop the caching of web addresses for the duration of the up time of the system.

The last method is only advised in the case of a recurring problem with DNS names as this will make web browsing a relatively slower experience.