Tip 40: The dodge. Hopefully because of tip 36 this won’t happen, but if you get a question you really don’t know how to answer then SAY SO.
Waffling or dodging is the worst approach – credibility is eliminated immediately if you do that.
Saying just “I don’t know that” is better, though still not perhaps the best response.
Saying “I don’t know but I will find out by [this method]” is the best “save” you can hope for here. (And if you obviously write yourself a note to do it you can reinforce how well organized and diligent you are!)