I want to know if an IP address is in use on LAN.

Usually ping works,which can tell me whether the remote machine is alive or dead.
But it does not always do the job.
even if I 've got a result like this:
C:\>ping 192.168.28.168

Pinging 192.168.28.168 with 32 bytes of data:

Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 192.168.28.168:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

When I change my IP address to 192.168.28.168, Windows informs me that "The IP address 192.168.28.168 is already in use."
How can I know the IP is in use before I changed my IP to that and Windows popups the dialog?
What is the mechanism of Windows examing if an IP is in use?