setup MIC to MIC passwordless ssh

Hello,

Is it possible to setup MIC to MIC passwordless ssh?

When I ssh from one MIC to another:

root@mic0 ~]# ssh mic1
The authenticity of host 'mic1 (192.168.1.21)' can't be established.
ECDSA key fingerprint is -------------------------------------------------------
Are you sure you want to continue connecting (yes/no)? ^C
[root@mic0 ~]# 

What are the exact requirements for setup?

Just to be more clear, the requirement is that upon rebooting mpss, I would like to skip the "Are you sure you want to continue connecting?..." dialogue when issueing an ssh command from one MIC to another.

All MIC's, mic0-mic7, must meet this requirement for username "root"

More details:

Are you sure you want to continue connecting (yes/no)? 
Warning: Permanently added 'mic1,192.168.1.21' (ECDSA) to the list of known hosts.
[root@mic0 ~]# ssh mic1 ls -a     
.
..
.profile
.ssh
[root@mic0 ~]# 

Thanks,

Rob