CAT is a national level entrance exam for getting admission in IIMs and top B Schools all over India. So it is compulsory to give CAT examination if you want to get admission in IIMs. For getting admission in top most IIMs like IIM Ahmedabad, Bangalore, Calcutta etc. You must score a percentile more than 95 in CAT. As you are in 2nd year now, you should start preparing for CAT if you're interested in this. Your graduation marks as well as 10th and 12th marks are also important.