After Google Penguin 1.0 and 2.0 update the SEO community considers links from guest blog posting as safe practice and guest blogging is on rise day by day. There are some common questions which every one in search marketing industry raise these days
Will Google hit guest blogging?
How Google will find the spam blog or blog posts?
How many post to be done in a month?
How many links to be created by guest blogging?
To some extent we have got the answers of above questions. Recently Google revised link scheme definitions and clearly mentioned
“Large-scale article marketing or guest posting campaigns with keyword-rich anchor text links”
We can easily conclude from above change in Google link scheme if you do large scale guest blogging just to build inbound links on keyword-rich anchor text it will be considered part of a link scheme and a violation of Google’s Webmaster Guidelines. Such practice of guest blog posting will be penalized by Google. It is Google’s warning to not do large scale guest posting with keyword-rich anchor text just to increase domain authority or page rank. Google is going to target “Links with optimized anchor text” phrase.
Please note that large scale guest blog posting with intention to manipulate keyword-rich anchor text is bad not all guest posting.
Mark Traphagen on Google+ explained the positive side of this change
In reality, based on what Google actually does (not just what they threaten), I believe that kind of posting and even linking is going to be fine. Google doesn’t go through every post on the Internet looking for single violations. They couldn’t possibly.
Rather they look for big patterns that are the footprint of those who are planting links only to manipulate a specific keyword. That’s why the new guidelines say “large-scale” efforts of this type.
Google will never be against guest posts where a legitimate authority is sharing valuable insights or new information on his topic, and they will never be against links that make contextual sense and enhance the value of the content