[aldarn]

This is a great example of why the OPs question could be a good or terrible interview question -- it's not clear if they want the obvious technical solution (comparing datetimes) or a wider discussion about "what is a date time and how is the data represented", "what are the real world / business implications", "here is existing technology using intervals that will solve it" etc as you mentioned.

In my experience interviewers are usually looking for the technical solution despite the business oriented solution usually being much more applicable (and thus relevant) in the day to day role.

Key thing to remember here as an interview candidate is to clarify with the interviewer the scope of the question and the nature of the answer they're looking for. If for instance the interviewer starts with the simple technical solution and then probes the business aspects this might be a nicely rounded question.

[Benjammer]

My company asks a question during engineering interviews that is overly simple, but a bit vaguely defined on purpose. The main objective is to see if they can ask clarification questions to determine precise requirements, which is something that every engineer does daily on the job.