Mastercard interview questions

There were 4 rounds of process: Round 1: Online Assessment test which was conducted on hirepro of 1.5hr. @ coding question were given. Those who have solved 2 question or 1 question + 12/15 testcases of other question were selected for interview process. Total 40 students has been selected from 200. Only CS/IT branch was allowed. Round 2(Duration: 40-45min): Technical Interview: Have some discussion on vector and array with respect to DSA question. Then he moved to ACID properties of dbms, then transaction discussion in detail regarding all states, roll back, commit and saved point. Then he has seen my resume. He asked some questions about my project like why i made these projects and why i am using mongodb not sql and vice versa. Difference between relational and non-relation databases. Detailed discussion on jwt token , structure of it. Is it safe or not? how does it store information. How does it transfer information? Round 3(Duration: 30mins): Some basic questions regarding system design. what is horizontal and vertical scaling . When do we use what and why? Then wholesome discussion on my projects. Round 4(HR Round): Some basic puzzles and questions like where do u see yourself in next 5 years. If there is conflict in team, then how do u handle it? Total 4 students are selected out of 40