Can you really issue a take down for an interview question? The text of one, ok, but the essence of the question itself?

Surely not?

I wonder if you have to sign an NDA to be asked the questions? IMO these cutesy interview questions have gone over the top and I think I'm going to use this as my proof.

But NDAs are for trade secrets and DMCA is only for copyright.

Not to mention that a NDA only provides a way to attack the person who signed it, and has no effect on anybody else even if they further spread the information.

If the interview question consists of some copyrightable source code with questions about it, why not?

It seems highly unlikely that even if there was source code, the candidate would be able to remember it with a high enough level of detail to warrant this.

maybe it was an online pre-interview question that you get to solve at home within a given timeframe?