[ntp:questions] two machines syncing to the same master - hardware issues?

David Taylor david-taylor at blueyonder.co.uk.invalid
Thu May 30 19:47:44 UTC 2013

On 30/05/2013 19:18, matthew.garman at gmail.com wrote:
> I have two servers in the same physical location that are syncing to the same two NTP servers.  My understanding is that these NTP servers are in the same building as my servers, and we are connected via an in-building connection.  In other words, network jitter should be reasonably low (at least compared to the Internet, for example).
> My two machines are somewhat different: "oldbox" is running NTP 4.2.2 as ships with RedHat 5.7; "newbox" is running NTP 4.2.4 as ships with RedHat 6.3.
> Oldbox has been used as our company's central NTP server for many years.  But the machine is not dedicated to this purpose: it performs other business functions that are erratic in nature.  So we procured newbox to act as a poor-man's dedicated NTP server.  In other words, newbox does nothing but NTP.
> What we've found is that newbox generally has a much larger offset to its NTP peer, compared to oldbox.  Likewise, newbox's offset also varies much more over time.

For a central server I would hope that you are using a really good clock 
- such as the PPS signal from a GPS making that server stratum-1.  I see 
offsets usually less than 10 microseconds.

The current NTP is 4.2.6, and I am using the development version 
4.2.7p368 on all of my PCs.
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