While my background is in development (20+ years experience), I've spent the last decade managing fairly large projects that always have a database component. In that time I've hired dozens of DBAs for various positions, and come across more than a few whose answers to those questions might be more frightening than the ones listed. I've also come across aces, whose depth of knowledge impressed me greatly. Some of those aces just didn't work out, but the DBA types who couldn't answer simple questions have never worked out.
What strikes me though is that so many clearly inappropriate candidates apply for the positions in the first place. I find that roughly one third of my interviewees simply don't have basic skill sets applicable to the opportunity, no matter how well delineated the skill requirements are. I also find that with some of these people there is a degree of bluster that makes the head spin, and sometimes makes me, as an interviewer, want to shake them and beg them to find a career outside the industry.
But my best experience ever in hiring is what I wanted to relate. I had a candidate several years back whose CV was incredible, whose conversational knowledge was impressive, and who, during the Q&A part of the interview, began by setting a reference book on the desk in front of himself and saying, "I'm guessing the answers to all these questions are in here somewhere...but let's see how I do. You owe me coffee if I get more than 80% of them right." Not only did he get the first 15 questions right, and 18 out of 22 correct, he had the job before we reached the third question. It was a combination of pointing out the fact that a reference book and a human being are different, and because his first answer was given with a minimal use of terminology, kept short, and expressed in a way a non-DBA could understand.
What that taught me was that the best DBAs, like the best developers, have strong communication skills, are aware of their limitations as human beings, and are confident that they can overcome challenges. These are all traits lacking in the DBAs who haven't a clue, but then in a very real sense they aren't actually DBAs at all.