Clear DNS Cache to Fix Network Issues

By Stephen Bucaro

If you are frequently receiving error messages when trying to access websites, you may need to clear your DNS cache. The internet uses the Domain Name System (DNS) to maintain an index of all public websites and their corresponding IP addresses. When you type a URL like bucarotechelp.com into your browser address bar, it asks the router for the related IP address. If the router does not have the URL with related IP address, it has a DNS server address stored, so it asks the DNS server for the IP address. The DNS server finds the IP address related to bucarotechelp.com so your browser can then load the requested webpage.

It's quicker to have a local copy of URLs and related IP address of all recent website visits and attempted visits to websites. So your computer stores a database called the DNS cache. The computer checks its local DNS cache first to speed up the process before the request is sent out to the DNS server.

A DNS cache can become poisoned when computer viruses insert invalid entries into the cache. When troubleshooting internet connectivity issues, a computer administrator may flush (clear) the DNS cache to eliminate cache poisoning as a possible cause. Clearing the DNS cache removes all entries, including valid entries, which forces your computer to repopulate those URLs and related IP addresses as you access those websites.

To clear the DNS cache, open a Command Prompt which you can do by opening the Start menu and typing "Command Prompt" in the search bar. Enter a password or confirmation if requested. Next to the command prompt type: ipconfig /flushdns You know it worked when you see the "DNS Resolver Cache Successfully flushed" message. As mentioned earlier, a router also has a DNS cache, which you can flush as a troubleshooting step by rebooting it.

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