Heartbeat Discovery is actually re-discovery using another discovery method. Heartbeat Discovery periodically refreshes the information in the SMS discovery database. Without Heartbeat Discovery, new discovery data only is written to the discovery database when a client logs on to or off of the network. Therefore, Heartbeat Discovery is useful when you have users who log on to client computers less frequently than you want their discovery data to be refreshed.
Note You can only use Heartbeat Discovery to refresh discovery data obtained through Windows Networking Logon Discovery.
Configure Heartbeat Discovery
Discovery Methods Configuration Overview