The server’s host key is not cached in the registry. You have no guarantee
that the server is the computer you think it is. The server’s rsa2 key
fingerprint is: <string>. If you trust this host, hit **Yes** to add the key to
PuTTY’s cache and carry on connecting. If you want to carry on connecting just
once, without adding the key to the cache, hit No. If you do not trust this
host, hit Cancel to abandon the connection.