Was there a racial element to the interview? Probably, given that black men are very rare in IT and that people are not used to dealing with unusual things in many ways. However, these sound like typical dumbass "brainteaser" questions:
So now questions like, "How does one measure the amount of water passing a particular point in a river?" or "Why can you not see the Moon during the day?" are being asked.
The problem is they're not really brainteasers, in that they're fun "impossible" or "off the wall" questions.
The first is a rather fun question and has had many solutions with a rather interesting history. If you've happened to done any civil engineering, then you may have covered streamflow measurement in which case the first answer is somewhat nuanced and based on the size of the river, number of measurements required and various other constraints.
The second one is the old "why are manhole covers round" in that the question is outright wrong.