CentOS 6.5 configuration ssh key-free login to execute pssh command explanation

[root@bogon ]# pssh -H [email protected] -i uptime
[1] 11:00:36 [FAILURE] [email protected] Exited with error code 255
Stderr: The authenticity of host '192.168.245.129 (192.168.245.129)' can't be established.
RSA key fingerprint is 84:2d:70:33:1c:45:fa:e6:4b:94:72:7e:10:98:7c:a8.
Are you sure you want to continue connecting (yes/no)? 
Host key verification failed.

[root@bogon tmp]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
9e:14:9a:cc:8d:9b:fd:51:c5:68:24:e1:ce:c6:d7:33 root@bogon
The key's randomart image is:
+--[RSA 2048]----+
| o.. |
| .oo |
| . . oo |
| o = = . o |
| * S = o E |
| * ooo |
| o + . |
| . . |
| . |
+-----------------+

[[email protected]]#ll
total 8
-rw------- 1 root root 1675 Aug 22 11:06 id_rsa
-rw-r--r-- 1 root root 392 Aug 22 11:06 id_rsa.pub

[root@bogon .ssh]# ssh-copy-id -i /root/.ssh/id_rsa.pub [email protected]
The authenticity of host '192.168.245.129 (192.168.245.129)' can't be established.
RSA key fingerprint is 84:2d:70:33:1c:45:fa:e6:4b:94:72:7e:10:98:7c:a8.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.245.129' (RSA) to the list of known hosts.
reverse mapping checking getaddrinfo for bogon [192.168.245.129] failed - POSSIBLE BREAK-IN ATTEMPT!
[email protected]'s password: 
Now try logging into the machine, with "ssh '[email protected]'", and check in:
 .ssh/authorized_keys
to make sure we haven't added extra keys that you weren't expecting.

[root@bogon .ssh]# pssh -H [email protected] -i uptime
[1] 11:10:39 [SUCCESS] [email protected]
 20:10:39 up 2:07, 1 user, load average: 0.00, 0.00, 0.00