[A2A] Yes, they are forced to do both, but they are only forced to do research somewhat well, but nobody really cares about teaching. Everyone is supposed to teach classes at IIT. Even, our deputy director at IIT Delhi used to teach us, that too an 8 am class. He was a very good teacher. But, even if you don't teach well, no one cares.
Everyone is forced to do research because all the promotions and "respect" is determined by how much money you bring in grants to the institute and to some extent by how much you publish. The situation is similar in American universities.