I remember studying cut-through forwarding in a class and thinking it was obviously going to be used everywhere.

Then I was disappointed to enter the real world of networking and learn that it wasn’t actually used as often as I had been led to believe due to conflicting with higher priority features.

So the interview may have been a conflict between textbook learning and the Google engineer’s practical experience. It’s tough to encounter that conflict in interviews because you get two people talking past each other.