No you do not need to give any other exam before appearing for CAT. CAT is a direct entrance exam for MBA and PGDM courses mainly in IIMs and other top business schools in India. You just need to have a graduation degree or be in your final year of graduation to be eligible. There is no requirement to clear any other test before taking CAT. You can register for it when the application form is out usually around August and then appear for the exam in November.