MacOS Server versions prior to Lion are based on an open source foundation called Darwin and use open industry standards and protocols.

Also, it was optionally pre-installed on the Mac Mini and Mac Pro and was sold separately for use on any Macintosh computer meeting its minimum requirements. Mac OS X Server was provided as the operating system for Xserve computers, rack mounted server computers designed by Apple.

2.8 Mac OS X Server 10.6 (Snow Leopard Server).

2.7 Mac OS X Server 10.5 (Leopard Server).

The latest version of macOS server only includes functionality related to user and group management, Xsan, and mobile device management through profiles. MacOS Server at one point provided network services such as a mail transfer agent, AFP and SMB servers, an LDAP server, and a domain name server, as well as server applications including a Web server, database, and calendar server.

Versions of Mac OS X Server prior to version 10.7 “Lion” were sold as complete, standalone server operating systems starting with Mac OS X 10.7 “Lion,” Mac OS X Server (and its successors OS X Server and macOS Server) have been offered as add-on software packages, sold through the Mac App Store, that are installed on top of a corresponding macOS installation. macOS Server adds server functionality and system administration tools to macOS and provides tools to manage both macOS-based computers and iOS-based devices. MacOS Server, formerly Mac OS X Server and OS X Server, is a series of Unix-like server operating systems developed by Apple Inc., based on macOS and later add-on software packages for the latter.

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