Adding NTP server with POWERCLI

>Add NTP Server:
Get-VMHost -Name * | Add-VmHostNtpServer -NtpServer "ntp-server"

>Restart NTP service:
Get-VMHostService * | Where-Object {$_.key -eq "ntpd"} | Restart-VMHostService -Confirm:$false

>Set NTP to start and stop with the host (policy ON):
Get-VMHost * | Get-VMHostService |  where {$_.Key -eq "ntpd"} | Set-VMHostService -Policy On