Some times you have noticed that a new broadband user gets irritating while surfing the internet, and internet gets down but it is still connected because most of the DNS clients gets cache and  the results of name resolution requests. It speeds up name resolution if multiple looks are done to the same address, such as it is common while browsing the web.

Sometimes a bad DNS entry will be cached and you will need to either flush the DNS cache to get rid of it, or wait up to 24 hours for it to be dropped from the cache automatically.

To come out of this just go to

• START->RUN->CMD or COMMAND.
• A Command Window will open
• Just type IPCONFIG/FLUSHDNS

The ipconfig /flushdns command provides you with a means to flush and reset the contents of the DNS client resolver cache. Within matter of second bad DNS will flush out and you can surf the internet easily.