All sorts of questions - "What's the best way to do X?", "How would it impact security?", "Why we need this?", "What happens if this fails?", "Remind me how this works?", "Am I thinking in the right direction?"

Even more questions to the business / CEO ( Why this, why now )

"why", "how", "can we", "who can"?

Just try to be humble in the world where nobody knows anything (including yourself)... :)