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Hi Atul. Based on your question I have spent some time trying to locate an official reply from Google on this topic. I was not able to find such a statement. Therefore, I modified my reply from "Google will discount links (from the same C-block)..." to "Google can discount..." What we know for certain is Google is a very intelligent organization and they have entire teams dedicated to ensuring search quality is maintained. Google specifically wants to ensure links are independent in nature. Links from the same C-block is clearly an indicator the link may have been influenced and is not independent. I would even go further and share it is common belief amongst SEO professionals that C-blocks affect links. The entire concept of "SEO hosting" is based upon offering hosting with different C blocks. A great white board friday discussion on this topic: http://www.seomoz.org/blog/which-link-metrics-should-i-use-part-1-of-2-whiteboard-friday Rand shared in the above video "the best single metric, non-aggregated metric, that we've got to predict Google's rankings with correlation data is the number of Linking C-Blocks." TL;DR - There is strong evidence which indicates C-blocks information is used as a ranking factor, but I was unable to locate any specific statement from Google confirming this information.