Please cut-and-paste how you run the “actual full command”, perhaps redacted a bit if you wish. That enables people to help you much faster.
Best,
Chin Fang
What authentication do you have setup with the hosts? user/password? ssh key?
If your full command is
$ansible webservers -u
then I am afraid that it’s incorrect. You didn’t specify a module with the -m option. Actually, to do what you wish to do (a quick test), why not follow the ansible official doc using the ping module?
ansible webservers -m ping --ask-pass
I also suggest you to use the -v option, like this:
ansible webservers -m ping --ask-pass -v
Best,
Chin Fang