[ntp:questions] NTP internal server?

Richard B. Gilbert rgilbert88 at comcast.net
Fri Oct 27 01:07:49 UTC 2006

metogroup at group.com wrote:
> I am looking to implement an 'internal' NTP server (preferably freeware) 
> on a Win 2003 server so that I can broadcast NTP across Windows, Unix and 
> S400 servers.
> Has anyone been successful in doing this and can recommend a utility to me 
> please?
> Access to NTP externally is not permitted.
> Thank you in advance.

The problem is not so much the software; that's readily available and 
free, but the time source.  The typical computer does not keep time very 
well; most systems gain or lose several seconds a day.  Using such a 
clock as a time source means that, while all your systems are more or 
less in synchronization none of them have the correct time. In a really 
bad case, all the systems could gain or lose twenty to thirty minutes a 

Normally, an NTP client will use a server that gets time directly or 
indirectly, from a hardware reference clock.  A hardware reference clock 
  gets accurate time from a source traceable to NIST by some form of 
electronic communication.   Typical reference clocks are GPS receivers, 
WWV receivers (NIST HF broadcast station), WWVB receivers (NIST VLF 
broadcast station) or equivalent services operated the the national 
standards laboratories of other countries.  Your computer can even make 
a telephone call to NIST to find out what time it is.

You appear to be operating under restrictions that will make it 
difficult or impossible to keep correct time.  If everybody having the 
same incorrect time, maybe wildly incorrect time, satisfies you then go 
to it.

If you are allowed to install and use a GPS timing receiver ($85 US and 
up)you can use it to synchronize a local server to the correct time and 
then provide that time to your network.  For more money (a lot more, I'm 
afraid) you can get an NTP server in a box with either a GPS receiver or 
a receiver for the reference signal from a CDMA cellular telephone base 
station.  You plug in the power cable, you connect it to your internal 
network, configure it with an IP address and subnet mask and you're up 
and running.  Either approach will allow you to keep your network 
synchronized within five milliseconds, or better, of the correct time.

The software is available, in source form, from

A pre-built Windows version is also available:

Linux and most Unix systems ship with some version of the NTP daemon. 
This can be anywhere between a few months to a decade out of date; Sun 
Solaris, for example, ships with a version almost ten years old! It 
still works but that's about all you can say for it.

More information about the questions mailing list