As a general rule, when interviewing potential employees, it's best not to ask a question unless you know why you're asking it. If you don't know why, chances are the question isn't worth asking. Think about where you want your questions to lead before you ask them. Think of questions as qualifying tools used to help you get the information you need to make the right decision about a candidate. What are the answers you're hoping to get from an outstanding candidate?
Excerpted from Attracting & Rewarding Outstanding Employees