Root Cause Analysis enables prevention of problems, by analyzing problems that happened in the past. As a QA focusing on corrective measures of root causes is more effective than simply treating the symptoms of a problem or event which helps us to encounter more issue for same defect under defect clustering & perform effectively when accomplish through a systematic process with conclusions backed up by evidence, usually there are more than one root cause for any problem or event & we should investigate every cause so that the focus of investigation and analysis through problem identification back & forth of event occurred.