I'd like to use kerberos with NFS4 and my question is, prior to switching kerberos on:
What happens to existing, already exported shares when I switch kerberos on? Will then all shares be automatically
use kerberos or do I have to export them using the -sec=krb5... option?
Not really export, but define export policy that is using krb5. Changes to export policy are instantaneous as far as I know, but may apply to new mount requests only.