Apple released OS X Server 2.2 for Mountain Lion late on Thursday. The update for Apple's server software added a new Caching Service for App Store purchases and software updates, and more.
OS X Server update improves locally stored app installer and update support
The version 2.2 update also fixed problems with the Adaptive Firewall, Calendar and Mail services, Contacts service, Messages service, and Profile Manager.
Apple noted that DHCP service may not automatically start after updating from a previous version of the software. To fix the problem, launch the service from the command line: sudo serveradmin start postgres
OS X Server 2.2 is a free update and is available via Software Update.