google-public-dns-a.google.com is better known as 22.214.171.124
This is one of the host names for Google Public DNS. This is a free Domain Name System (DNS) service offered to Internet users worldwide by Google. It functions as a recursive name server.
The service was launched by Google in December 2009.
See also google-public-dns-b.google.com which is better known as 126.96.36.199.