Domain Name servers are responsible for resolving the web address that you type in on the address bar of your web browser into machine understandable IP addresses to locate the servers.
Almost all the internet service providers have their own dns servers for this purpose… It is not strict rule that you have to use this dns servers for address resolution always.. some other public and free dns servers are available today.
Some of these kind of dns servers provides security against vulnerabilities in the internet, some are very much faster than the dns servers of your ISP..
The ip of best public dns servers available are
google public dns
8.8.8.8
8.8.4.4
opendns
208.67.220.220
208.67.222.222
dns advantage
156.154.70.1
156.154.71.1
others
209.244.0.3
209.244.0.4
In Linux place the DNS IP’s in /etc/resolve.conf file.
In windows place the DNS IP’s where you place your general DNS IP:
(like as shown in the figure);
