Hey, admissions in any IIT's or NIT's depends on their cut offs which are some what different for every year depending on some factors such as 1)Number of applicants 2)Difficulty level of exam 3)Seats available for each course 4) Previous year cutoff trends. These cutoffs are different for different courses and different institutes. I have provided a link below where you can check the previous years cutoffs as per your course and institute location which will give an idea of how the selections of students is carried out. Hope this information is of help.Wish u good luck for your admissions.

http://www.engineering.careers360.com/articles/gate-cutoff-for-iits