一直对 SCCM 2007 中 AD System Discovery 和 AD System Group Discovery 方式的概念云里雾里，AD 中没有相应的概念。
今天在 SCCM 2007 的在线 Library 中发现了微软对这个问题进行了回答，原文如下：
Active Directory System Discovery retrieves details about the computer, such as computer name, Active Directory container name, IP address, and Active Directory site. It generates a data discovery record (DDR) for each computer it discovers in Active Directory Domain Services.
Active Directory System Group Discovery works only for systems that are already discovered and assigned to the local primary site and any direct child secondary sites. Active Directory System Group Discovery is not available for secondary sites. If a resource has been discovered and is assigned to the site, Active Directory System Group Discovery extends other discovery methods by retrieving details such as organizational unit, global groups, universal groups, and nested groups. Active Directory System Group Discovery cannot discover a computer that has not already been discovered by another method.