London falls back on the tried-and-true "I can see everything everywhere" point of view to tell his story. It's a smart call, since he has to show us things out in the wild involving animals that can't, you know, speak, as well as the internal workings of a wolf-dog's mind.
He shifts his character focus in the early chapters, starting with Hank and Bill on their sled: "In advance of the dogs, on wide snowshoes, toiled a man. At the rear of the sled toiled a second man" (1.3). A few chapters later, he crosses over to Kiche, who's the "first to spring away from the cornered man in his circle of dying flame" (4.1).
Then he basically settles into following White Fang around, using his omniscient point of view like a documentary filmmaker to follow one specific subject. He's close enough to White Fang to know what the wolf-dog is thinking and feeling, as in this passage: "He was not in the least disturbed by desire to find out the reason for the difference between his father and himself. Logic and physics were no part of his mental make-up" (6.11). That closeness keeps the narrative lean and sparse, just the way London likes it. It also plants us firmly in White Fang's camp, even when he's doing awful things like eating other dogs.