Assuming asking for B.tech, You can check the eligibility to get admission in IIST given below.

The Eligibility :

• 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.
• Candidates belonging to General category (GEN) and Other Backward Classes(OBC)categories must have been born on or after October 1,1992.Candidatesbelonging toScheduledCaste (SC),Scheduled Tribes (ST)andPersons with Disabilities (PD)categories must have bornon or after October 1,1987.
• The date of birth as recorded in the highschool/first board or equivalent will be accepted.

For further information you can  through with given below link.

IIST Eligibility