As reported in March, the FBI has uncovered a network of rogue DNS serversand has taken steps to disable them. DNS (Domain Name System) is an Internet service that converts user-friendly domain names into the numerical Internet protocol (IP) addresses that computers use to talk to each other

When you enter a domain name, such as www.fbi.gov, in your browser address bar, your computer contacts DNS servers to determine the IP address for the website. Your computer then uses this IP address to locate and connect to the website

DNSChanger is malicious software created by cybercriminals to redirect the Internet traffic of millions of unsuspecting users to websites where the thieves have profited from advertisements. All computers still infected with DNSChanger malware will no longer be able to access websites, email, chat, or social networking sites like Facebook after July 9th

Most of us will have a difficult time manually changing these settings on our own. To help with this, McAfee has released a free tool to you find out if you are infected or not

To see if you are infected with the DNSChanger virus visit http://www.siteadvisor.com/dns_checker.htmlthen click on the "Check Now" button. If your computer is fine, you will receive a green check message and if your computer is infected you will see a red X mark. You can then download a free update to clean up your PC and restore your Internet settings

It is quite possible that if your computer is infected with this malware, it may also be infected with other malware. To protect yourself you should:

Make sure your PC has comprehensive protection with antivirus, antispyware, anti-phishing, antispam and a firewall

Set up regular updates of your operating system so you get critical security patches and keep your browser updated too

Be cautious of clicking links in the body of an email

Stay safe!

Robert Siciliano is an Online Security Evangelist to McAfee. Watch him discussing information he found on used electronic devices YouTube. (Disclosures)