Makes host key checking the default behavior but can be disabled in ansible.cfg or by environment variable.

examples/ansible.cfg

@@ -22,6 +22,9 @@ sudo_user      = root
 transport      = paramiko
 remote_port    = 22
 
+# uncomment this to disable SSH key host checking
+#host_checking = False
+
 # change this for alternative sudo implementations
 sudo_exe = sudo