A reservation ensures that a DHCP client is always assigned the same IP address. To add a reservation, on the Action menu, ...

A reservation ensures that a DHCP client is always assigned the same IP address.  To add a reservation, on the Action menu, click New Reservation.  Note: An exclusion prevents a DHCP client from ever obtaining an address from a specified address range.  Exclusion ranges can be defined in Address Pool.  For more information about reservations and exclusions, see online Help.