Basic Server - Basic Servers are unmodified versions of the Halo Dedicated Server. These servers will be given just the basic security.
Advance Server - Advanced Servers modified versions of the Halo Dedicated Server. These servers are given the latest security patches, along with the latest patches to improve the performance of the server.
Duel Servers - Duel Servers are servers that allow three players to connect to them. This allows for a match between two people. The extra slot is designed for an opening for a referee/spectator. *Duel Servers are treated as Advanced Public Servers unless otherwise requested from the customer.
Public Servers - Public servers are servers that are put up onto the halo servers list.
Private Servers - Private Servers are servers that can only be accessed by people who know the direct IP of the server. These servers are sometimes used by people who want clan only servers, but don't want to put on a password.