Is there anything here?

The Reading:

Shoyoroku - Case 51: Hogen's "Boat or Land"

Hogen asked Senior Monk Kaku,
  "Did you come by boat or by land?"
Kaku said,
  "By boat."
Hogen said,
  "Where is the boat?"
Kaku said,
  "The boat is on the river."
After Kaku had withdrawn, Hogen asked a monk nearby,
  "You tell me, did that monk who was here just now have the eye or not?"


Discussion:

How do we tell the difference between a Zen Question and any other kind of question?  When someone offers us a Question or an Answer, how do we know?

Who was Hogen putting the question to?  Was it Kaku or the monk nearby?