Hi, there is actually a guide for that here in the documentation:
https://techdocs.broadcom.com/us/en/vmware-cis/cloud-director/vmware-cloud-director/10-5/vmware-cloud-director-installation-and-upgrade-guide-10-5/deployment-uprade-and-administration-of-the-vcd-appliance-install/vcd-appliance-administration-install/edit-the-dns-settings-of-your-vcd-appliance-install.html