Nutanix platform timing guidelines state that Prism Central requires accurate clock synchronization to ensure proper authentication, event logging, certificate validation, and cluster orchestration. The documentation details that "NTP must be configured to a reachable, reliable time source, and best practice is to configure Prism Central to use an external, independent, standards-based NTP server." Using a Domain Controller is acceptable only if the DC itself is properly synchronized with an authoritative external NTP source, but Nutanix strongly recommends specifying the external source directly in Prism Central for consistency across hypervisors and multi-cluster environments. Adding a DNS server IP is not time-related. Adding a hostname is valid only if it resolves to a functioning NTP server, but the question requires the correct method, not the acceptable syntax.
Therefore, selecting an external NTP server is the correct and recommended configuration.