This will prevent configuration of root SSH between all nodes in the cluster (including installation of a default private key on all nodes).
sshbetweennodes: Comma separated list of groups of compute nodes to enable passwordless
root ssh to the nodes during install or running 'xdsh -K'. The default
is ALLGROUPS. Set to NOGROUPS to disable.
This will prevent configuration of root SSH between all nodes in the cluster (including installation of a default private key on all nodes).