Hello vivek first of all if you main aim is to go in railway then IITs doesn't play any role in getting you into Railway so you don't have to prepare for JEE mains JEE advanced you have to prepare for UPSC and RRB exams that are important for railway recruitment.

To join Railways as career you dont need any IIT degree, you can take up any degree course.

For admission unto IIT, you need science stream and vakid score in Jee advanced.
Post your graduation go for  UPSC exams for making career into IRPS that is Indian Raliway Personnel Services.

Students can get great posts in Ministry of raikways, Zonal and Department Heads in Railways production units.

All details and eligibility criteria shared below.
https://www.careerindia.com/upsc/irps-exam-e10.html

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