What you are explaining is very imp. My son did his MS in maths from IISER Tirupathi, he did his thesis from IIT Tirupathi. When he applied for PhD abroad, it is preferred every where in Europe.
Sir JEE mains rank tho IISC bangalore ki BS course apply chesam, aithe appudu Jee mains and advance ki option save chesi apply chesam IAT option save cheyaledhu, eppudu IISER ki apply chesam kani IISC bangalore ki thorough IAT vellalante second application cheyakudadu edit option unde chance undhaa please reply sir