about preparatory course in dhanbad
Dear aspirant
You need to ask question clearly so.that we ca. Help you. However I am suggesting on general basis.
I am afraid to confirm you that " preparatory rank" is not really a rank . Every IIT has separate quota seats for SC , ST , OBC etc. These seats go vacant in every year . So the vacant seats are allotted to students of that respective category for a one year course . They are trained in the IITs If they pass then they are eligible for undergraduate courses at IITs and they get direct admission in those . However students doing preparatory courses can sit for JEE ADVANCED next year also.
Best wishes.