I applied through a university. They asked for my CV and my IT capabilities. After the initial CV review, I got an email to go to that university for the interview. The first step was to do a small exam in half an hour, with some technical and theoretical questions. After finishing the exam, I was received by two CERN employees, a Staff and a Section Leader, and while one of them took notes, the other one was asking me questions about why I answered that and challenging me to propose something better