SASTRA DEEMED UNIVERSITY takes admission on its own cutoff generated by a normalisation of many factors such as +2 marks, JEE mains score, state of domicile, etc. So a lot many characters decide if you will get admitted or not. For the purpose of Stream 1 and Stream 2 Rankings they consider the total GP secured by the student. In case of a tie in stream rankings they check Mathematics, Physics, Chemistry's GP of second year to ascertain the rank in order of merit.
There is also a JEE mains entry scheme. The percentile score obtained in Mathematics, Physics, Chemistry and total percentile is considered.
You can know more about admission at their official website.