Microsoft Software Engineer(Internship) interview questions

Was contacted by the recruiter a day after submitting my application online. The first round was a 30 min on-campus interview. Mostly behavioral questions and one technical question which was something along the lines of reversing every word in a string. The interviewer was friendly. Got selected for the second round of interview at Redmond. There were 4 back to back interviews. The first was an easy programming question about vectors/arrays. But it had a lot of edge cases to cover and the interviewer expected me to ask a lot of questions. The second interview involved thinking about how the touchButton function works internally in iOS app dev and reading some C# code (you were allowed to ask him questions on the syntax). The third round had a design question. The first three rounds were not that hard. The fourth interview was completely random though. It involved OS and ML concepts - classes that I have not taken yet (The interviewer had any idea about my skills and resume).