I can tell you a NTP joke but timing has to be perfect

The CVMs that comprise a Nutanix cluster get their time by syncing to a single member which is known as the NTP Leader (aka Genesis Master). This node will be responsible for syncing with whatever NTP servers the customer added to Prism. When NTP is properly configured, the Leader CVM will set its own clock to the time provided by the server and then all other CVMs will sync with the Leader's time. 

For AHV clusters, the same list of servers used by the NTP Leader will be configured on each host to sync with independently. All other hypervisors need to have NTP configured separately using their unique management tools. By default User VMs sync their time with the local hypervisor where they are running, but users can configure their machines to sync with local or internet-based NTP servers as well.

Importance of NTP:

1. If there is a power outage and cvm’s pick up wrong time it can prevent the cluster to start

2. It’s very difficult if you're trying to RCA any issue

Commands:

1. To check ntp status

nutanix@CVM:~$ ncc health_checks network_checks check_ntp

2. To check if all the cvm is able to sync with ntp servers

nutanix@CVM:~$ allssh ntpq -pn

For details regarding NTP please make use of following article

https://portal.nutanix.com/page/documents/details?targetId=Web-Console-Guide-Prism-v58:wc-ntp-server-time-sync-recommendations-c.html

https://portal.nutanix.com/page/documents/kbs/details?targetId=kA032000000bmjeCAA