Only do connection if I already know the destination?

[M Rubon]

I have an automated remote script that connects to a set of known
servers.  I never want be prompted to add a new host key if the server
is missing from .ssh/known_hosts.   If the key is missing, the client
should just immediately exit.

Dropbear seems to give me the option of relaxing the host key checks
(-y -y).  Is there an option to make them more strict?

M

p.s. OpenSSH client option "StrictHostKeyChecking yes" is basically
what I am looking for.