1

which is the best way to configure ntp server ? on switch side or in the windows server dc???

4 Spice ups
2

The Domain controller (DC) holding the PDC Emulator role should be the authoritative time source for domain joined computers. That DC then points at an NTP source for its time.

3

I don’t have the backup documentation handy, but Windows Domain controllers are not a full NTP implementation and should not be used as a time source for NTP clients. They will provide time but it’s not preferred.

4

Here’s one reason why you would not use a domain controller as an NTP source for other devices: VMware Knowledge Base

5

A simple scenario is to setup an NTP server on one switch - have this switch use the same time source as your AD server. So if you have a gps timesource for example they should both use that. If not AD is defaultig to ntp from the internet - define which NTP servers it should use and use the same for the switch.

Then if you have other network devices that require NTP set them as clients to your switch. Specifically if you have multiple switches you could set more than one to use the external ntp source and then setup a peer group, then if one loses it’s true source they will keep reasonably in sync.

6

How do you define best? What’s your purpose? What are your constraints? What have you already looked up? And will ntp be sufficient or will you need higher precision? Which reference clock(s) do you have? Is it for one site or multi-site? Which operating systems in which version are you using on your infrastructure and for main users?

There is no best way. There might be a most appropriate way. If you lookup Microsofts ntp docu, it’s good and incomplete. You’ll find complementary info in Internet, partially based on info of the Microsoft team in charge of time implementation, partially based on expert knowledge of network time standards. Of course there exists also much of less trustful info in Internet. If you have high precision time needs, then ntp is no longer recommended for those usages. But you may have a dual time configuration, one for high precision needs and ntp for the remainder. And your preferences might be different if you’re running a pure Microsoft shop or have a mixed infrastructure.

You’ll find a first introduction on ntp in wikipedia . This is not limited to a single operating system. And it is typical that your network equipment doesn’t run Windows.

As you mentioned Windows server, you may start to read here with Microsofts docu . Don’t limit yourself to the article. It is just one out of a series of different times. And if you look onto the navigation bar on the left, you also see that you’re able to generate a PDF for the whole subject for download or viewing. This could be a starting point for understanding and preparing design of network time infrastructure and service for your infrastructure. And I just have seen that it has been updated since the last time I looked at it. As you reply to my previous questions, I may provide additional info if I still find it. I know one expert who researched Internet time at my former university before I started my studies (on different subjects). It was a research project in cooperation with a major radio clock manufacturer of high precision clocks. This expert is in contact with the Microsoft team in charge of Windows time service code and he publishes articles on ntp and Internet time but he did not succeed to convince Microsoft to switch its implementation to full compliance with ntp. Microsoft strongly recommends to use such clocks as external reference for your network time design, regardless of which manufacturer. If your needs are lower, there exist cheaper alternatives while still following Microsofts recommendation of using reference clocks.

NTP is intended to run and distribute UTC, not local time. Since more than 10 years, Windows supports such a configuration and operation mode although it is not its standard mode. This mode and configuration is not included on the docu on Microsoft web sites, at least the last time I checked about a year ago. Microsofts implementation for that ntp standard mode has some limits. And using external time reference radio clocks is part of the solution to address these limits and not the only reason why such clocks are recommended.

If your motivation is not ntp itself and if you’re a pure Microsoft shop, you may consider Microsofts preferred time service configuration.