We have 3 tier environment and Heartbeat discovery is enabled on child primary servers as well as the secondary servers. Other Discovery mechanisms (Ad system discovery and AD system Group Discovery) are enabled only on child primary servers. Do we really need to enable the Heartbeat discovery on secondary sites (the answer is NO as per the below thread) ? Can somebody share the DDR process document (well written)? How does the discovery mechanism work (including initial AD discovery and how it is getting added to DB and which are the attributes getting updated by heartbeat discovery)? The below thread is also having most of the details about heartbeat discovery. http://social.technet.microsoft.com/Forums/en-US/configmgrsetup/thread/2a1e7eba-f3ef-4d20-b218-714171429ab6Anoop C Nair

Clients are not assigned to secondary sites therefore they do not get client agent settings from them. No need to enable it there. here's the flowcharts http://technet.microsoft.com/en-us/library/bb735871.aspx John Marcum | http://myitforum.com/cs2/blogs/jmarcum/|

As John is saying secondary sites dosn't really count when it comes to client agent settings. For all primary sites, you should enable heartbeat discovery.Kent Agerlund | http://scug.dk/ | The Danish community for System Center products

How does the discovery mechanism work (including initial AD discovery and how it is getting added to DB and which are the attributes getting updated by heartbeat discovery)? Heartbeat has nothing to do with other discovery methods plus it's the only one that is initiated by the client itself. That's included in a heartbeat DDR: SMS Unique Identifier Client Version Client Type Unknown Client NetBIOS Name Resource Domain OR Workgroup AD Site Name IP Addresses MAC Addresses IP Subnets Resource Names Operating System Name and Version Previous SMS UUID SMS UUID Change Date Hardware ID SMBIOS GUID SMS Installed Sites