Authenticating Remote Hosts
Remote Secure Shell servers are authenticated by a public-key procedure. The user checks the fingerprint of the remote server's public key. When the user has approved the public key, it is stored in the user's
$HOME/.ssh2 directory and will be used automatically thereafter.
The verification step requires user interaction, so even for users that are set up to run client programs unattended (Section Running Client Programs under MVS), the first connection, and every time the remote host's key is changed, must be done by a person who logs in as the user, accesses the remote server, and goes through the fingerprint check dialog.
See also Server Authentication with Public Keys.