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Clear Your DNS Resolver Cache Just To Be Safe

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So, you think going incognito or deleting your browsing history will keep your boss from finding inappropriate sites?  It does to some extent, but if someone really wanted to catch you in the act—whatever act that may be—then they wouldn’t have too much of a hard time.

We all know that your computer has to talk to a DNS service provider to translate the URL you type to an IP it can use.  Every time your computer has to resolve an address issue it’s cached in your systems DNS cache—basically, it’s your browsing history.  This browsing history isn’t restricted to your browser, it’s anytime your computer has to locate another server on the internet.

To find out what’s in your DNS cache is to bring up the command prompt in Windows and type the command:

ipconfig /displaydns

Now, the first thing you’ll notice is that a whole lot of information will appear, to the point that all of it can’t fit in the command prompt.  What you can do is take the output of the command and send it to a text file somewhere on your machine.

ipconfig /displaydns > c:\desired location

Now, when you open that file you’ll see information about the websites you’ve visited directly or indirectly.

You’ll see blocks like the one below; you might have multiple entries under each heading.

mail.google.com
—————————————-
Record Name . . . . . : mail.google.com
Record Type . . . . . : 5
Time To Live  . . . . : 151
Data Length . . . . . : 8
Section . . . . . . . : Answer
CNAME Record  . . . . : googlemail.l.google.com

Finally, how do you get rid of this, so that the cops knocking on your door have a harder time finding your browsing history—they’ll eventually find it, you’re just delaying them.  Just type the command below and your DNS cache will be cleared.

ipconfig /flushdns

Once you’ve typed that you’ll get a nice little message saying it was successful.

Windows IP Configuration

Successfully flushed the DNS Resolver Cache.

That’s it.  Your DNS cache is clean of whatever inappropriate sites you visited.

Written by Samir Banjanovic

October 6, 2009 at 2:53 am