The low threshold for available free addresses in
this scope. If the value for available free addresses
in this scope becomes equal to or less than this value,
a cnrDHCPScopeFreeAddrLowThreshold event is generated
for this scope. No more cnrDHCPScopeFreeAddrLowThreshold
events will be generated for this scope during this
execution of the DHCP server until the value for available
free addresses has exceeded the value of
cnrDHCPScopeFreeAddrHighThreshold.
This value may be expressed as either an absolute value
or a percentage; the units are specified by the value of
cnrDHCPScopeFreeAddrUnits.