ansible is not connecting with servers

[Ali Warrich]

Hi guys,
I am trying to run a playbook but that is not working for me. I am encountering by the same error again and again.
my ansible.cfg looks like:

[defaults]

# some basic default values...

inventory      = /etc/ansible/hosts

#library        = /usr/share/my_modules/

remote_tmp     = $HOME/.ansible/tmp

pattern        = *

forks          = 5

poll_interval  = 15

sudo_user      = root

ask_sudo_pass = True

#ask_pass      = True

transport      = ssh

#remote_port    = 22

module_lang    = C

and the error is :

 SSH Error: ssh: Could not resolve hostname ControlMaster=auto: Name or service not known

That's very strange to me. As when I am running another playbook it connects with all servers but when I only try to ping via ansible it gives me an error like this one.
Any one have any idea about it?