[ntp:questions] ntp documentation

Dennis Hilberg, Jr. timekeeper at dennishilberg.com.invalid
Thu Jan 17 02:51:35 UTC 2008

Pat Farrell wrote:
> On Fri, 04 Jan 2008 22:19:04 +0000, Steve Kostecke wrote:
>> The NTP FAQ is available at http://www.ntp.org/ntpfaq/NTP-a-faq.htm
> Thanks.
> Is there any documentation of the public graphs? 
> For instance, my server is at 
> http://www.pool.ntp.org/scores/
> I'm not sure what the 'offset' mean. Recently my graph shows lots of blue
> above the Y axis, I have no idea what that's telling me.
> Pat

The pool score/offset graphs are explained at the bottom of your server's 
score page where it says "What do the graphs mean?"

Quoted from the score page:

The Score graph

A couple of times an hour the pool system checks the time from your server 
and compares it to the local time. Points are deducted if the server can't 
be reached or if the time offset is more than 100ms (as measured relatively 
crudely from the monitoring systems). More points are deducted the bigger 
the offset is.

When the score goes down the background color in the top part of the chart 
will reflect how severely the "outage" is. The color scale goes from blue 
(very little) to yellow to orange to red (the server is several seconds off 
or unreachable). Because of how the graph is averaged out, you can't always 
infer what happened from the color. It's only meant as a tool to visualize 
trends. For more exact details of what the monitoring system found you can 
click on the CSV link.

The Offset graph

The monitoring system works roughly like an SNTP (RFC 2030) client, so it is 
more susceptible by random network latencies between the server and the 
monitoring system than a regular ntpd client would be. In other words: Don't 
be alarmed by the occasional large offset and please don't use the offset as 
an absolute performance metric.

Dennis Hilberg, Jr.     \  timekeeper(at)dennishilberg(dot)com
NTP Server Information:  \  http://saturn.dennishilberg.com/ntp.php

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