sir please tell me if NITs are good for MBA or not as backup option?

As far as i know and i am concerned it is preferrable to writ CAT exams again than join MBA in NITs....

Don't do that, try getting into some business school.

Hi Yes NIT's can be considered as a back up option if you are very keen to do MBA this year but currently I would suggest you to focus on getting as high as you can in CAT. If you need any help regarding your preparation you can join our telegram group :https://t.me/CatWithCracku link for the same.