Heh... so a DBA doesn't need to know what a Clustered Index is???
Sorry... Unless you're trying to hire a TRUE SYSTEM ONLY DBA, I find that laughable and even a bit disgusting.
Of course, the term "DBA" has been so bastardized over the last 20 years, you can't tell what you're getting nor even asking for anymore. It's like the old commercial where "If it doesn't say Sunkist, you don't know what you're getting". 😀
It reminds me of when I was interviewing someone who had a Phd in Mathematics (and I DID verify that). You might think that someone applying for the position of "Lead Developer" that also has a Phd in Mathematics might just some something about numbering systems. I drew the following on the board (1 4 base 16 is how it's interpreted) and asked him to convert it to base 10 .
He told me he would need a pencil and paper or a calculator to do the conversion.
You have to ask advanced people the simple stuff first or your going to hire an idiot. I've seen it happen way too many times. It's like the "how do you get the current date and time in T-SQL" I ask as the very first question of every interview and it has been an awesome litmus strip for how the rest of the interview was going to go.
Don't assume because the person has a whole can of alphabet soup after their name that they actually know anything practical. They just might not know how to use the can opener. 😉
If they're insulted by you starting with simple questions, then you don't want to hire them for that reason either,.