LANDesk uses two modes:
1 - Subnet directed broadcast to the subnet broadcast address where the machine was last seen
2 - Wake-On-WAN where an elected subnet representative will send the Magic Packet broadcast internally within the target subnet
The second method is only available from LDMS v9.5. Our Wake-On-WAN module takes this a few steps further if you are still encountering difficulties.
I hope this helps to answer your question.
LANDesk Silver ESP
The One-Stop Shop for LANDesk Enhancements
Update - WoW & State Notifier now integrate for even more functionality
Update - State Notifier now detects machine and user Idle states