Does search engine use whois info??

Yes they use whois information to detect possible cheaters, Google recently became ICANN accredited register, it means they have access to the whole whois database, A google PR lady said google dont have plans to become domain register but they use whois data to improve search engine results quality, so beware, Also google has an expired domain penalty they check whois to see when the site expires and if the domain is not renewed by the original owner immediately a penalty is imposed on it and is removed from google results for a period of 1 month to 2 years,