It is client side
/thread
OK, so start out by Opening multiplayer/zombies
Now while your in the lobby, change your name to something different, it will update in the lobby. But once you get in game. Your name is how you launched the game.
Example:
I launch the game with the name Hello, While in the lobby I change my name to Hi. When in game, My name will be Hello still, At least thats what it looks like, It may be client side but i'm not sure.
It is client side
/thread