NIT entrance exam pattern is listed here:

Exam pattern:

The entrance test will have two parts – Main Test and Advanced Test. Both the tests will be conducted on the same day.

The selection process for IITs and other central funded institutes (NIT, IIIT etc) will be different.

Selection to IITs will be a two step process. The first step will be filtering process.
n the second step, the top 50,000 students will be selected for the advanced test after taking into account their performance in the filtering step – 12th board marks and the main test. For selection to IITs, merit only in the advanced test will be considered.