Active is a Boolean property that indicates if the component is currently monitoring the network adapters and IP addresses in the local system. 

Changing the value in Active to True causes the TIdIPAddrMonThread in Thread to be created using CheckAdapters as the event handler for the OnTimerEvent in the thread. The Thread is executed. Please not that the Thread is neither created nor executed at design time. 

The initial values in IPAddresses are assigned when Active is set to True. 

Setting Active to False causes the Thread for the component to be terminated, freed, and released. 

Assign a procedure for the OnStatusChanged event handler proper to setting Active to True.

Thread CheckAdapters IPAddresses