Probably, you think that's easy. Listen to the question, think for a moment (or longer...if time allows) and explain your answer.
But when I looked at this blog post, I am a bit intrigued. For those who don't know who that guy is, he's Kir Kolyshkin. One of the main developer of OpenVZ, a container solution for Linux. Container is a kind of virtualization which is done in OS level. System calls are intercepted so every guest thinks he owns the whole system. But unlike User Mode Linux, OpenVZ is not using ptrace, but guest kernel is patched so system call is now routed to a "stub" in host kernel. So certainly, Kir is not average developer and far from mediocre level....
This paragraph is interesting:
"I think the talk was well received and I had about 10 different interesting questions, one is puzzling enough so I was not able to provide a good answer. This is definitely a sign of a good audience."
Most of the time, especially when some (doubtly) educated people receive tough question, he will turn into defending mode or attack the questioner back. But Kir thinks differently. He admitted he can not answer all questions, a normal thing for normal human being. And he appreciated that.
I wish this kind of attitute is something we can learn and practice in our everyday life.....