Shutting down and Restarting a Nutanix Cluster requires some considerations and ensuring proper steps are followed - in order to bring up your VMs & data in a healthy and consistent state.
Nutanix is a Hypervisor agnostic platform, it supports AHV, Hyper-V, ESXi and XEN. This makes it all the more important to read the following Nutanix KB, which details the steps required to gracefully shutdown and restart a Nutanix cluster with any of the hypervisors.
Nutanix KB : How to Shut Down a Cluster and Start it Again?