Domain Name Service (or Server or System) is an internet service that translate easily memorized domain names into IP numbers and vice-versa. DNS Servers can be better understands as Yellow page directory to the Internet. Every ISP runs DNS services for their customers and users. A user can also runs DNS service for its own. There are many DNS servers which are open for all, commonly known as Public DNS Servers. IP addresses of main Public DNS Servers are :- Google Public DNS Servers 1. 8.8.8.8 2. 8.8.4.4 3. 2001:4860:4860::8888 4. 2001:4860:4860::8844 Level 3 Public DNS Servers 5. 4.2.2.1 6. 4.2.2.2 7. 4.2.2.3 8. 4.2.2.4 9. 4.2.2.5 10. 4.2.2.6 OpenDNS Public DNS Servers 11. 208.67.222.222 12. 208.67.222.222 13. 2620:0:ccc::2 14. 2620:0:ccd::2 Norton Public DNS Servers 15. 198.153.192.1 16. 198.153.194.1 Comodo Secure Public DNS Server 17. 8.26.56.26 18. 8.20.247.20 Other Public DNS Server 19.