ansible all -m ping

localhost | UNREACHABLE! => {
     "changed": false,
     "msg": "Failed to connect to the host via ssh:  ssh:  connect to host localhost port 22:  No route to hostrn",
}
192.168.20.21 | SUCCESS => {
     "changed": false,
     "ping": "pong"
}

cat /etc/group | grep -i 'oracle'
ansible:x:1001:oracle

[local]
localhost
#192.168.20.22  ansible_ssh_pass=oracle  ansible_ssh_user=oracle

[oracle12c]
192.168.20.21  ansible_ssh_pass=oracle  ansible_ssh_user=oracle

127.0.0.1  localhost  localhost.localdomain  localhost4  localhost4.localdomain4
::1        localhost  localhost.localdomain  localhost6  localhost6.localdomain6

192.168.20.21  redacted  hostname
192.168.20.22  redacted  hostname