At a job interview in 2016, I was given a fairly typical "design Twitter" whiteboard problem, so I started doing a fairly typical thing involving load balancers

At a job interview in 2016, I was given a fairly typical "design Twitter" whiteboard problem, so I started doing a fairly typical thing involving load balancers and Nginx and the like. The topic of the database came up, and I asked "Do we care more about consistency or availability?". He responded back with "we want both". I said "I mean, I would like both too but I'm pretty sure we can only get one" He disagreed and we went back and forth, and eventually I pull out my phone and pull up the Wikipedia for CAP theorem. He eventually (and begrudgingly) agreed and said "umm, I guess availability", so I used Cassandra and moved on with it, though five minutes were wasted with this pointless argument. To be fair, they did make me an offer, and it was even a decent enough offer (though I ended up taking a different job), but I remember being kind of flabbergasted that I had to explain CAP theorem to a person who had like a decade more experience than I did. It's not like CAP theorem is this super deep arcane topic; I'm pretty sure it's one of the first things you learn about when getting into distributed systems. It was certainly one of the first thing that I learned about.