The command used to modify iDRAC IP address is the following one:
racadm setniccfg -s <IPv4Address> <netmask> <IPv4 gateway>
admin@ecs-node-04:~> sudo -i racadm setniccfg -s 10.16.20.22 255.255.255.0 10.16.20.254
Static IP configuration enabled and modified successfully