Domain Name Service [DNS] servers are the roadmaps of the Internet. They direct your browser to the correct website. Computers use numbers [called an IP address] to identify themselves, but humans have a hard time remembering numbers. Enter the DNS server. When you type www.google.com the DNS server looks it up in a table and returns the number 208.67.217.230, which is the IP address of Google. When you first connected to the Internet your Internet Service Provider [ISP] told your computer how to find its DNS server.
DNS poisoning is an increasing problem on the Internet. If your machine is compromised then it will point to a rogue DNS server. This server will return incorrect numbers and you will be sent to the wrong website. These websites can be mockups of legitimate sites that are phishing for personal data, malicious sites that try to install software on your machine, or sites that are full of advertisements.
If you notice that you are being sent to the wrong websites or a familiar site doesn’t look quite right, contact your ISP or local computer geek and ask them to verify that your computer is using the right DNS server.
Posted by Mugly 