If you attempt to make a connection to a managed node (e.g. target system) and the node has not been configured for SSH, the following will most likely be displayed.

Refer to our article on Getting Started with SSH.

server1.example.com | UNREACHABLE! => {	
    "changed": false,
    "msg": "Failed to connect to the host via ssh: Permission denied (publickey, password).",
    "unreachable": true 
}