NTP Servers

[ITMgrWynne]

Being a novice to vSphere/vCenter, I am not sure the proper steps to setting up NTP Servers. Is there any good documentation out there? Or is someone able to provide me so assistance? I have 2 Hosts and neither have NTP servers setup. Thank you.

[daphnissov]

Not sure exactly what you're asking. If it's "how do I configure NTP servers in ESXi hosts" then it's basically as simple as what you're showing. You edit the NTP configuration to specify your NTP servers. Use of an even number is not recommended. Use either one or three. Set the daemon to start upon boot-up. That's basically it.

[ITMgrWynne]

daphnissov​

Thank you! That is what I was looking for. Are there recommend NTP Servers to use? I guess that part I do not know either. Thanks again!

[daphnissov]

There are tons of devices/services that implement this function that range from dedicated software to switches and routers. You'll just have to see what makes the most sense in your infrastructure.

[Alex_Romeo]

Hi,

In addition to the responses of the other technicians, on page 67 of the attached manual you can find configuration details.

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also in this link it is well explained:

https://www.vladan.fr/configure-esxi-6-5-network-time-protocol-ntp-via-host-client/

ARomeo

[diegoarroyo]

Hello daphnissov

Why an even number of ntp servers is not recommended?

Also do you know what is needed to survive reboots?

On vsphere 7.0.0 (Build 15843807) with ntp servers configured, Start and stop with host policy, and first manual start of ntp server, if I reboot/power off the machine, ntp is allwas stopped but ntp servers and policy configuration is keept.

Thanks and Best Regards,

Diego Arroyo

[daphnissov]

You need an odd number of NTP servers to have a majority when there is a time discrepancy. If someone blindfolded you and dumped you in a forest at night and you needed to know the time, you'd consult a watch/clock. What if you were wearing two watches which displayed different time? Which one is correct? You need a third watch to see which of the two are correct, thereby having a majority.

[diegoarroyo]

Thanks daphnissov

But is it not needed an odd number for that.

For selecting offsite ntp servers, section "5.3.3 Upstream Time Server Quantity" in http://support.ntp.org/bin/view/Support/SelectingOffsiteNTPServers said at least three, but does not said that 4 is worse, same in RFC 8633: Network Time Protocol Best Current Practices

Best Regards,

Diego Arroyo

[daphnissov]

Having more than three becomes problematic. Generally, it should be either one or three, but not two or four.