To clear Dns Cache or flush dns cache can be done by the rebooting the machine, but this is not the most practical way of doing this. The resolver cache has a preset default period of storage time of 24 hours, which holds the IP address in the dns cache. This time period of 24 hour can produce an error if the address in the (ULR) Uniform Resource Locator has altered before the period is over. This particular dns error or 404 pages in your browser is not the most of common occurrences but some times will happen. This can also some times happen when there are high Internet traffic large loads on the main server making it will through out a negative response because the Uniform Resource Locator is temporarily busy. Resulting in the old records - negative responses still located in the local cache. The preset default period is about five to six minutes or more before negative response clearing dns cache is fixed and restored to the correct value.
To clear dns cache and flush dns cache.






Go to the Start Run and Click it.



Then you Enter the command line ipconfig /flushdns in the Open dialog textbox.
Next click on the OK button then the flushing cache is all done.

To stop the placing of negative entries into cache dns, alter the registry key in. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ Dnscache\Parameters
make a fresh DWORD with a name of NegativeCacheTime and set it value to zero.