Diploma Candidates can appear for JEE Mains but cannot use their JEE Mains score to seek admission in NITs, IIITs, CFTIs. To qualify for JEE Mains, there is no minimum aggregate criteria. But if you want to join NITs, IIITs or CFTIs then you should score a minimum aggregate of 75% only in your 12th. 11th marks aren't considered. And then to appear for JEE Advanced which is the gateway for admission to IITs, you will need to fulfill the 75% aggregate condition. Now it is 75% for General Category and 65% for Reserved Categories. So how much you score in 12th is what matters to secure your eligibility for NITs, IIITs, CFTIs and JEE Advanced. But because you have pursued Polytechnic, though you can appear for JEE Mains, you cannot take admission in NITs, IIITs, and CFTIs. Now for this year the minimum aggregate in 12th also has been removed but the criteria that Diploma is not allowed remains. You can take admission to remaining State run Government Engineering Colleges, Private Engineering Colleges but not NITs, IIITs and CFTIs. If you can help us with the State you belong to, we can help you with best Colleges from that State.