Which connection type is used for online play?

I am in Europe and I am currently in most games, experiencing very harsh connection lag which varies from game to game, but in some games I get no lag at all, which I assume is because I was host of the game and everyone is connecting to me instead of me connecting to them. I just want to know if all players are connected to a server for a game, or the game chooses a host out of one of the players.

I may not have an answer to if there is a dedicated server or not, but I do know they had some lag issues all over the map in terms of online play and I’m sure they are just working some bugs out.