If you see this error message or something like WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!  you should don’t worry if you know your server RSA key was really changed, like your server was re installed. What to do?

The RSA host key for linux4you.tk has changed,
and the key for the corresponding IP address 5.199.164.77
is unchanged. This could either mean that
DNS SPOOFING is happening or the IP address for the host
and its host key have changed at the same time.

ssh-keygen -R linux4you.tk