The matchmaking system present in the console versions (and those PC versions that do not use dedicated servers) of Call of Duty games works by gathering players into a lobby (a room players are grouped in before a match).One player is chosen as the host, who hosts the server that all other players connect to.
Capacity on demand (COD) is a purchasing option that allows companies to receive equipment with more computer processing, storage or other capacity than the company needs at the time of purchase, and have that extra capacity remain unused and unpaid for until the company actually requires it.