Technically stat neither returns nor fills in the inode, because the actual structure of the inode can vary by filesystem, and the inode will contain more field

Technically stat neither returns nor fills in the inode, because the actual structure of the inode can vary by filesystem, and the inode will contain more fields than struct stat. In a recruiting situation, if the recruiter is going all "right and wrong" on the interviewee, they should know these dirty details. I also disagree on the ethernet address length. You know how long IPv4 addresses are, you know how long IPv6 addresses are, why would it be so extraordinary to also know how long MAC adresses are? I think it could be useful to find out in an interview whether the applicant knows stuff because they have actually implemented low-level code and gained an intricate understanding, or whether they just did used some high level APIs and were never interested in more details than "I have a handle right here, it does all I need". For some positions that would be an important distinction. Personally, if I were interviewing people, I'd hire the guy that explains something to me that I did not know, but that I find interesting and would have attempted to understand, too.