It has to do with your internal urls.

www.domain.com/internal-page?printable-version
http://www.domain.com/internal-page?...rce=feedburner
www.domain.com/internal-page?sessionid=123


The above examples are all the same as www.domain.com/internal-page, but search engines might pick up other versions of that same URL.

Both Bing and Google detect them, and they usually treat them appropriately. They make the settings available since some sites are complex and their auto-detection might be off. 99% of the time you don't have to do anything if it's saying it found query parameters.

You could however, make sure that all versions of your URLs have rel=canonical pointing to the version you want indexed. Having your query parameters detected properly and canonical tags in place, will reduce duplicate content issues and improve crawl efficiency and % of the site indexed (especially important for large sites).

Thanks for your response..so you dont think it would be negative towards rankings?