task 1.2 command switchport mode dynamic desirable

hi all, i'm trying to do task 1.2

but problem with command switchport dynamic desirable not seen in my switch

Rack1SW1(config)#interface range ethernet 2/0-2

Rack1SW1(config-if-range)#sw

Rack1SW1(config-if-range)#switchport mode ?

  access        Set trunking mode to ACCESS unconditionally

  dot1q-tunnel  set trunking mode to TUNNEL unconditionally

  private-vlan  Set the mode to private-vlan host or promiscuous

  trunk         Set trunking mode to TRUNK unconditionally

Rack1SW1(config-if-range)#switchport mode dynamic desirable

                                                                        ^   

% Invalid input detected at '^' marker.

Rack1SW1(config-if-range)#

somebody can help

thks

jimmy