hi,

see you did not mention which exam you are asking about. however for engineering admission in iits or nits or bits which has no direct admission policy. all good institute needs entrance test. like jee advance exam is for iit btech admission. however 12th marks criteria for iits or nits is 75% in 12th for general category, 65% for sc/st or if you are among top 20 students who got highest marks in 12th exam in any board then you are also eligible to apply for iits or nits btech admission.