Each site in the Configuration Manager 2007 hierarchy can be independently enabled or disabled for Wake On LAN. When a Wake On LAN activity is targeted at client computers, the wake-up transmission is sent only to client computers that are assigned to that site. Because advertisements and software update deployments are inherited by child sites, the site server in the child site is responsible for sending the wake-up transmissions to its assigned clients if the site is enabled for Wake On LAN.
If the child site is not enabled for Wake On LAN, client computers in that site will not be sent wake-up packets.
As an example, if you target a software update deployment to a collection containing computers at multiple sites, wake up packets will be sent only to collection members assigned to sites where Wake On LAN is enabled.