Describe the narrator of “The Cask of Amontillado.” Is this story told in first, second, or third person point-of-view? Is this narrator reliable or unreliable? Explain your answers and use evidence from the story to support your responses.

"The Cask of Amontillado" is told in the first-person point of view. We know this from the very first line, in which the narrator, Montresor, states the following:

THE thousand injuries of Fortunato I had borne . . .

The "I" is the give-away that this is the first-person point of view. Montresor is telling his own story in his own words, as he understands it.
Montresor is not a reliable narrator. He is far too close to his subject and wants to justify the horrible murder of Fortunato he committed fifty years before. We can't expect him to provide an accurate or objective recital of events.
Evidence of Montresor's unreliability is the vagueness of his motivation for a particularly cruel form of murder. All he says is that he had, as noted in the quoted line above, borne a "thousand injuries," but he doesn't state what these were. At no point does he describe anything Fortunato has done that would warrant walling him up to die. At worst, Fortunato, from what we can gather, has been snobbish and superior toward him, but if that were a reason for walling a person up, the world itself would be walled up with bodies.