On every networked game I worked on, there was one guy working on the in-game network code. Nobody else had the faintest idea how it worked, though it was typically fairly well known at least what not to do in order to make his life no more difficult.

(On two of those projects, I was the lead programmer, responsible, in theory, at some level, for all the code that went into the game. And I still couldn't have answered your question.)