The key aspects in Outcome-Based Education (OBE) is the assessment of course outcomes. At the initial stage of OBE implementation, the Course Outcomes (CO's) for each course are defined based on the Programme Outcome (PO's) and other requirements. At the end of each course, the COs needs to be assessed and evaluated, to check whether it has been attained or not. This paper describes the background of the method used to assess the attainment of the COs and the results produced for the Computer Networking (CNE-17429) course in diploma engineering. This assessment was conducted for Computer Science & Engineering program for second year diploma with strength of 57 students. The method uses data that has been obtained from student's marks in final theory and practical exams. A computerized system using spreadsheet has been developed based on this method to expedite the analysis process. The findings are then used for continuous quality improvement.