Linux SSH cannot connect to other hosts

For example, SSH 10.0.1.23, the following conditions occur:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ warning:remote HOST Identification has changed! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT is POSSIBLE this SOMEONE is DOING SOMETHING nasty!
Someone could is eavesdropping on your right now (Man-in-the-middle attack)!
It is also possible, the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
D8:6a:2a:5a:22:f6:cc:ae:6a:01:1b:22:59:92:a9:7d.
Please contact your system administrator.
Add correct host key in/root/.ssh/known_hosts to get rid of the this message.
Offending key in/root/.ssh/known_hosts:16
RSA host key for 10.0.1.23 had changed and you have requested strict checking.
Host Key verification failed.

Workaround: Ssh-keygen-r 10.0.1.23

Note: Ssh-keygen usage See http://linux.chinaunix.net/techdoc/beginner/2010/01/12/1153509.shtml

Linux SSH cannot connect to other hosts