The value of the object tmnxDhcpServerPoolMaxLeaseTime specifies
the maximum lease time.
If there is no lease time configured in DHCP option 51 (in the user
database, or in the tmnxDhcpSvrPoolOptionTable, or in the
tmnxDhcpSvrSubnetOptionTable), then this value is encoded
in option 51 of the DHCP reply message.
The maximum lease time can only be configured to a value that is
larger than or equal to the value configured in object
tmnxDhcpServerPoolMinLeaseTime.