when you do the client install (msi package or single exe )
the client package wil have information about the management server
once the installtion is complete the clients will try connecting to the manger using the information in the sylink.xml file
once the package is created even if the entire sepm server is down the package can stil be installed on clients
however for them to report and display in the SEPM console it should be up and running.
heart beat is a continious procedure, it would keep checking the manger specified in the sylink.xml file in a specified interval ( 5 min is default)
smc.exe is the process responsible for this process
in the subsequent heartbeat the client wil get connected to the manager when its up and running