DNS is an online directory which resolves host names to corresponding IP addresses. Google Public DNS is a global DNS (Domain Name System) which is provided as a free service by the search engine giant Google which can be used as alternative DNS instead of using the DNS assigned by your ISP. In order to use Google DNS you should configure your DNS server settings with IP addresses 8.8.8.8, 8.8.4.4 for IPV4 and 2001:4860:4860::8888, 2001:4860:4860::8844 for IPV6. As per the recent reports, Google Public DNS receives around seventy billion requests per day and is largest public DNS.