# Windows: Searching for a good open source Full NTP Client (not a simple NTP Client)?

Due to strange behaviors in the system clock (it seems a bit crazy: battery is OK, but it loses many minutes randomly) I need to sync the time of my computer automatically via internet. I am testing NetTime that seems to be working fine, but if has a 15 minutes frequency limit.
Its docs say:

The vast majority of users should find that NetTime more than meets their needs, however if you have specific requirements for very accurate time, I recommend that you investigate installing a full NTP client. Although you can set NetTime to sync more frequently to compensate for an inaccurate system clock, this isn't really recommended because of the greater strain that it puts onto the public NTP servers. A full NTP client has extra features to ensure better time accuracy (normally well below 10 milliseconds even between time syncs) by adjusting the rate that the system clock runs at. If you are administering a large number of PCs for an organization, it's also recommended that you configure a full NTP client on your network and have the rest of your systems sync to it with an SNTP client - this reduces the load on the public time servers even further as well as ensuring that all systems are in sync with a single time source.

So, I wanna try such Full NTP Client, but googling about those words shows me the same results (even the same NetTime program as one of the first results) that I obtain when searching for any other NTP Client.

Could someone, please, recommend me any (open source preferred) Full NTP Client? I am running Windows 7 SP1, but a generic any-Windows solution would be better.

• Did you read up on what is NTP and how it (basically) works? – Angelo Fuchs Oct 20 '14 at 7:42
• @AngeloNeuschitzer, indeed I did. I have managed some Windows networks by syncing the time of all computers (NTP clients) with one of them (NTP Server), managed firewall matters to open the appropriate port, and regkeys to activate the NTP services. But, as long as Beginning with Windows Server 2003 and Windows Vista, a compliant implementation of full NTP is included (according to WikiPedia en.wikipedia.org/wiki/Network_Time_Protocol#cite_note-19 ), I don't understand why should I need any other Full NTP Client, or why is it supposed to reduce stress on the NTP Internet servers. – Sopalajo de Arrierez Oct 20 '14 at 13:46
• @AngeloNeuschitzer, some more info from WikiPedia (same link as above) that don't set things clear:  The fully developed NTPv4 implementation is intended for [...] servers with multiple upstream servers and multiple downstream servers. I did not wrote down all that stuff on the original question because I was not sure to be adding relevant info to the problem, and I assume questions on this forum should try to be not too chatty. – Sopalajo de Arrierez Oct 20 '14 at 13:50
• You are right, not too chatty is good. But showing that you have tried to solve this yourself (by applying it) is positive. You might want to go to a tech chat channel though and ask there the "why is that not good" question. Then you will see the difference (or lack thereof) from a "full NTP client" to a "simple NTP client" and then understand this question yourself, come back and answer it then yourself, we appreciate that. – Angelo Fuchs Oct 20 '14 at 15:16
• What about SuperUser, @AngeloNeuschitzer? Could I ask the differences there? ServerFault seems not to be the appropriate place, and StackExchange is more designed for programming problems? I made my question here at SoftwareRecs because I was planning to understand the differences via experimentation, but as long as we have no (until now) a clear reponse for some Full NTP Client, I guess I will have to search in another places. – Sopalajo de Arrierez Oct 20 '14 at 15:33

There is one canonical NTP server software provided by the NTP project. This software has been developed collaboratively over many years and is the one that everybody uses as the reference implementation of an NTP server. It is production ready and is high quality. I strongly suspect that this is the specific software that NetTime is referring to when they say "full NTP client".

The software was originally developed for Unix systems, but some people have built the same software for Windows. Here is one such build which is packaged with an installer: http://www.meinbergglobal.com/english/sw/ntp.htm I have not used that particular Windows build, but I have used the same NTP server software on FreeBSD for many years.

• Could you please elaborate? Is this that thing named Full NTP Client program? Why should it be considered different from another NTP Client program, like the referenced in the original question? – Sopalajo de Arrierez Oct 19 '14 at 21:48
• @AngeloNeuschitzer yes, I have used that NTP server for years. I have not used the Windows build, but it is the same software as everybody else uses. This NTP server can certainly be considered a "full NTP client" because it is the original NTP code. I'm not sure what else can be said here, and I'm not sure why this deserves a downvote. The OP was having trouble using Google to find this software. – Greg Hewgill Oct 20 '14 at 7:55
• @AngeloNeuschitzer: Thanks, I've updated my answer. – Greg Hewgill Oct 20 '14 at 15:35
• @GregHewgill Great! Thank you. – Angelo Fuchs Oct 21 '14 at 7:56

My solution for XP is a batch file using NetTime.exe:

1. Start NetTime.exe.
2. ping -n 3 127.0.0.1 > nul
3. taskkill /f /IM nettime.exe

I think with any task scheduler you can start it how often you want.