Google Public DNS was announced on December 3, 2009,[1] in an effort described as "making the web faster and more secure.
Previously, Google Public DNS accepted and forwarded DNSSEC-formatted messages but did not perform validation.
A common attack vector is to interfere with a DNS service to achieve redirection of web pages from legitimate to malicious servers.
[11] Google stated that for the purposes of performance and security, the querying IP address will be deleted after 24–48 hours, but Internet service provider (ISP) and location information are stored permanently on their servers.
The block was the result of earlier remarks by Prime Minister Tayyip Erdogan who vowed to "wipe out Twitter" following damaging allegations of corruption in his inner circle.
The method became popular after it was determined that a simple domain name block was used to enforce the ban, which would easily be bypassed by using an alternate DNS resolver.