No, it is not mandatory to appear for all three parts of the CSIR NET exam. The three parts of the exam are: Part A: This part consists of General Aptitude questions, which are common to all subjects. It is compulsory for all candidates to attempt this part. Part B: This part consists of subject-related multiple-choice questions (MCQs). The number of questions and the total marks for this part vary depending on the subject. Part C: This part consists of higher value questions, which are designed to test the candidates' knowledge of scientific concepts and their ability to analyze and apply them. This part also varies in terms of the number of questions and total marks for each subject. Candidates can choose to appear for only Part A and Part B, or for all three parts of the exam, depending on their preference. However, candidates who wish to be considered for the award of Junior Research Fellowship (JRF) must appear for all three parts of the exam and secure the minimum qualifying marks in each part as per the CSIR NET eligibility criteria. Candidates who qualify for Lectureship (LS) are not required to appear for Part C of the exam.