The encapsulation dot1Q 20 command has not been configured.​Refer to curriculum topic: 6.3.3The steps to configure inter-VLAN routing must be completed in a specific order. Before configuring an IP address on a subinterface, the encapsulation dot1q VLAN_id command must be specified first. Explanation: The error that is displayed in the configuration of inter-VLAN routing on router CiscoVille is caused by the fact that the router has been configured with the wrong IP address. The correct IP address for the router should be 172.16.1.1.