Google is a popular company for web products. There are lots of web services provided by it. In of them Google Public DNS is one of the most used service by computer users. Google public DNS is free, global Domain Name System (DNS) which is used as alternative to our default Domain Name System. The DNS protocol is one of the important component web infrastructure. In other word it is a phone book like service which says IP address by web address (URL) . When we go to any web address(URL) first our browser connected with Domain Name Server. Then that server gives the IP address of the server where the respective web pages are located and our browser goes to the IP address which is given by the DNS (Domain Name System)