The 10.7.5 update is recommended for all servers currently running Lion Server. This update includes general operating system fixes that enhance the stability, compatibility, migration and security of your server and specific fixes for:

maintaining Spotlight index when changing share point settings
creating and connecting to Open Directory master
improved reliability of password authentication
using Software Update Server to automatically download and enable software updates
reliably booting NetRestore images created with System Image Utility
using Profile Manager to set the Mobility sync frequency settings for mobile accounts
improved reliability when changing an Xsan metadata controller into a client


This update also includes all the changes included in the 10.7.4 update.
For detailed information on this update, please visit this website: http://support.apple.com/kb/HT5314.
For detailed information on security updates, please visit this website: http://support.apple.com/kb/HT1222.

Requirements:
OS X Lion 10.7 Server