343 confirms Halo MCC uses Cloud Servers for Multiplayer after latest update
One of the many complaints that people have had with Halo: The Master Chief Collection is that the game appeared not to be using Microsoft's own Xbox Cloud Compute (Azure) servers for multiplayer games and games seems to have been using the same format as the Xbox 360 titles.
In the Original Xbox and Xbox 360 era, Halo matches were hosted in a peer-to-peer fashion, which meant that one player would be designated by the system as Host and all other players would be dependent on his performance: So if the host had a poor Internet connection, everyone suffered. Or worse, the Host would always have the best connection to the game and therefore have an unfair advantage.
One of Microsoft's big pushes for the Xbox One was the Cloud Compute strategy, where studios could essentially use Microsoft's own Azure cloud service to host Multiplayer matches and thereby give everyone an equal chance at the game and provide a more consistent performance.
While the multiplayer launch of The Master Chief Collection could best be described as bumpy, Frank O'Connor from Halo studio 343 Industries revealed to community members on NeoGAF that Halo had a fall back for multiplayer games if it could not reach the dedicated servers: It would use peer-to-peer networking, as before.
Since then the community has been calling for dedicated servers, and blaming poor performance on this peer-to-peer networking.
In announcing the Spartan Ops content update for Halo 4 in the Collection, 343 also addressed the question of Dedicated Servers, "We’ve seen many inquiries about dedicated server support for Halo: The Master Chief Collection. Dedicated servers have been up and running since launch, and we continue to optimize and improve connectivity." While the matchmaking in general had been encountering performance issues, many games were falling back to peer-to-peer.
343 confirmed that after weeks of diligent patching and fixing "The vast majority of games are being played on dedicated servers, but in the event that players cannot connect to a dedicated server, the lobby will stay together and the match will still occur on a peer-to-peer connection."
"Please be aware that you may connect to the dedicated server quickly enough that you won’t see the ‘connecting to dedicated server’ dialog. The absence of that dialog doesn’t mean that you’re not playing on a dedicated server.
Source: Halo WayPoint