IIST Thiruvanandhapuram takes the admission through JEE Advance only. You must have secured at least 75% aggregate marks in the Class XII (or equivalent) Boardexamination. The aggregate marks for SC, ST and PD candidates should be at least 65%. Themarks scoredin the following five subjects will be considered for calculating the aggregate marks. For further information about you can go through with given below link.

IIST Admission

Good Luck!

You will have to appear in Jee advanced as there is no separate exam which IIST accepts to provide admission as they only consider jee advanced score for the same. To know more about the same, you can go through the below article -

All about IIST

Hope this helps!!!