Windows 2000 Server also differs from Windows 2000 Professional in terms of the acceptance of incoming client connections. Windows 2000 Pro supports a maximum of 10 simultaneous connections, while in Windows 2000 Server the number of simultaneous connections supported is based on the number of CALs (client access licenses) available. Much like NT 4, two options exist in terms of licensing a server, Per Server and Per Seat. In Per Server licensing, each simultaneous client connection requires a CAL, while in Per Seat, each client requires a CAL. You can still switch from Per Server to Per Seat, but not vice versa. Note that you don’t require CALs for Telnet, FTP, or anonymous web server connections.
As in Windows NT, when you install Windows 2000 Server you will be asked whether you wish the system to be part of a workgroup or a domain. If made part of a workgroup, users who log on will be authenticated versus the local security database on the server. If made part of a domain, a computer account must be created for the system, either in advance or during the installation process. Note that the decision as to whether or not a computer becomes a domain controller is no longer made as part of the installation process. Unlike NT 4, domain controllers are created after Windows 2000 Server is installed. Promotions to domain controllers or demotions to member servers can be done without needing to reinstall the operating system.