To secure a Computer Science Engineering (CSE) seat in the main campus of a university, the required rank can vary significantly depending on the specific institution and its competitiveness. Generally, for top-tier institutions like IITs and NITs, you'll need a very high rank in the JEE (Joint Entrance Examination) Main or Advanced. For example, in older IITs, closing ranks for CSE can be within the 250-1000 range, while newer IITs might see cutoffs between 600 and 3000. For NITs, the cutoff can range from 1,000 to 25,000 depending on the specific NIT and its tier.