Confirm that the cluster recognizes the machines:

oc get nodes

Review the pending CSRs and ensure that you see the client requests with the Pending or Approved status for each machine that you added to the cluster:

oc get csr

To approve them individually, run the following command for each valid CSR:

oc adm certificate approve <csr_name>

Now that your client requests are approved, you must review the server requests for each machine that you added to the cluster:

oc get csr

If the remaining CSRs are not approved, and are in the Pending status, approve the CSRs for your cluster machines:

oc adm certificate approve <csr_name>

# To approve all pending CSRs, run the following command:
oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve

After all client and server CSRs have been approved, the machines have the Ready status. Verify this by running the following command:

oc get nodes