Use VMware Certificate Authority (VMCA) to provision the ESXi hosts in your environment unless your corporate policy requires that you use custom certificates. To use custom certificates with a different root CA, edit the advanced vCenter Server setting, vpxd.certmgmt.mode. After the change, the hosts are no longer automatically provisioned with VMCA certificates when you refresh the certificates. You are responsible for the certificate management in your environment.
You can use the advanced vCenter Server settings to change to thumbprint mode or to custom CA mode. Use thumbprint mode only as a fallback option.