My bank did this once - called me out of the blue and started asking for answers to security questions. I asked them how I could be sure it was definitely them

My bank did this once - called me out of the blue and started asking for answers to security questions. I asked them how I could be sure it was definitely them and they said to call the number on my card and ask for a particular department, which I did, and it turned out it was indeed genuine. The fact that they had an immediate answer to the question obviously means that they were asked this question all the time. I wonder how many people happily handed over the info? It seems that they now just play a recorded message asking to call, and then automatically hang up.