Comment by gfodor

A good way to get out ahead of this I didn't see mentioned is to just assume the person actually chased down the path you're proposing, and ask them about what happened when they did so. So for the example, "what happened with sshd?"

If the person considered sshd, this question will connect because it shows that you grok their problem solving process, assume they are at least as competent as you are, and you want to learn what surprises they encountered that neither of you would have realized beforehand. If they didn't consider sshd, this question doesn't seem to be likely to offend them since they will respond by inquiring why you think that was a potential solution and hopefully be prepared to learn.