Hey

You must note that admissions to Indian Institute of Science and Technology (IIST) are done on the basis of your JEE Advanced score. That means you need to clear JEE Mains and score well in JEE Advanced as well. By the formula, (100- NTA percentile score ) X 869010 /100 your rank comes out to be around 2.8-3 Lakhs All India, according to previous year record, sorry but you won't be able to sit for JEE Advanced. You must clear the JEE Mains cutoff to be eligible for JEE Advanced.

For more information regarding IIST, follow; IIST