This object specifies if the DHCP module should
generate 'cDhcpv4ServerSubnetFreeAddressHigh' notifications.
If value of this object is 'true', then the notification is
generated when the number of available IPv4 addresses for
a particular subnet has fallen below the value of
cDhcpv4ServerSubnetFreeAddrHighThreshold for that subnet.
If it is 'false', the notification is not generated.