NIT

Hello ! It depend on the cut off decided by the JEE that how much marks you are required to get admission in NIT but in case you dont get into NITS dont dishearten yourself,there are some premier private institution where you can get admission based on your JEE marks and can avail High scholarship.
some of these colleges are :
1. NIT
2. SRM
3. Lovely Professional University
i have heard that Lovely Professional University holds a good track of placements.this university has set a record for the highest number of placements from a single campus.
good luck !

For IITs Mention your board marks too.

check ur rank on shiksha predictor.

aproxx 43000 like in nit allahabad

To get admission in NITs you need to take JEE mains exam. The form for the same is available around Dec-Feb. Please visit the official JEE site for exact dates. You should have PCM in 12th as subjects and should score well in both 12th and JEE mains.

BITS is the absolute substitute for IITs .

Faculty of Thapar University is better than top NITs because thapar is more than 60 years old college. You can go through this link: http://thapar.edu/index.php/computer-science-engineering/faculty?sid=151:computer-science-engineering&site=1
in this you will get specifications and details about each and every faculty.

Can you be specific about which NIT.

There have been cases where a genius makes it through with going for coaching but I would say it is mandatory for a normal student.
A coaching class is trained to study the exam characteristics and have professional who can take you through the process is a well guided way. They also provide you with materials and experts to approach and since everyone avails it now. I believe it is a necessity. It is a decent investment for a bright future.