DNS (Domain Name System) is a resolution mechanism to translate, resolve and return real IP address of the serving machine against the fully qualified domain name of the URL (Uniform Resource Locator), aka link location. Whenever a domain has been resolved, the DNS resolution is stored and cached locally for future use.
The caching of DNS on local system ensure the fastest speed to resolve any domain name, and reducing hits, and directly load and burn of DNS name servers. However, it may cause some issues such as some websites and web pages not loading or cannot be contacted and connected when browsing, causing by changing of IP address or nameservers that hasn’t been reflected and refreshed on local copy.
The symptom is more obvious when user set web browser to use proxy to surf the Internet, and these sites now can be loaded properly.
When encountering any inaccessible or unable to load web page issue, one possible resolution is to try to flush (empty and reset) the DNS cache on the system. To flush the DNS on Windows system (Windows XP and Vista inclusive), follow these steps:
Click on Start button and then click on Run (alternatively just hit Windows + R keys) to open Run command dialog. Type Cmd into the Run box, and hit Enter. In Windows Vista, open an elevated command prompt.
A command prompt DOS window will open. Type ipconfig /flushdns and then press Enter to purge the DNS resolver cache.