A DNS server does not care and can not determine if a device is up.. its only job is to take name and give you ip address and then you can do anything you want with this ip address but that is not enough for you? I am confused.
I have the "setting", "Discover", "Name Preference" option set to "DNS,IP". However, my machines (all DHCP) keep getting re-discovered as new machines, or (worse) I get false readings on some machines because they have the IP address that used to belong to someone else. How do I fix this?