Domain Name System in short DNS helps to point website name to appropriate IP address of that website . By default your ISP (internet service provider) set their own DNS servers in your system. But if you unhappy with your ISP’s DNS servers because of its speed or any other thing then you can change it. So many free and paid DNS servers are available for you. Some comes with malware protection, blocking of adult content and some other features. Some Popular free DNS Service are listed below.