NTPsec

scratchy

Report generated: Wed Apr 2 06:15:04 2025 UTC
Start Time: Tue Apr 1 06:15:04 2025 UTC
End Time: Wed Apr 2 06:15:04 2025 UTC
Report Period: 1.0 days

Local Clock Time/Frequency Offsets

local offset plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Time Offset -1.167 -1.167 -0.768 -0.112 0.340 0.641 0.641 1.108 1.808 0.352 -0.151 ms -7.707 22.81
Local Clock Frequency Offset 21.187 21.187 21.203 21.340 21.602 21.637 21.637 0.399 0.450 0.141 21.384 ppm 3.392e+06 5.098e+08

The time and frequency offsets between the ntpd calculated time and the local system clock. Showing frequency offset (red, in parts per million, scale on right) and the time offset (blue, in μs, scale on left). Quick changes in time offset will lead to larger frequency offsets.

These are fields 3 (time) and 4 (frequency) from the loopstats log file.



Local RMS Time Jitter

local jitter plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Time Jitter 128.896 128.896 135.681 195.680 250.799 300.292 300.292 115.118 171.396 37.727 194.077 µs 83.91 405.6

The RMS Jitter of the local clock offset. In other words, how fast the local clock offset is changing.

Lower is better. An ideal system would be a horizontal line at 0μs.

RMS jitter is field 5 in the loopstats log file.



Local RMS Frequency Jitter

local stability plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Frequency Jitter 13.086 13.086 15.564 22.467 38.881 43.682 43.682 23.317 30.596 7.268 24.330 ppb 20.9 75.09

The RMS Frequency Jitter (aka wander) of the local clock's frequency. In other words, how fast the local clock changes frequency.

Lower is better. An ideal clock would be a horizontal line at 0ppm.

RMS Frequency Jitter is field 6 in the loopstats log file.



Local Clock Time Offset Histogram

local offset histogram plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Offset -1.167 -1.167 -0.768 -0.112 0.340 0.641 0.641 1.108 1.808 0.352 -0.151 ms -7.707 22.81

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats log file.



Server Offsets

peer offsets plot

The offset of all refclocks and servers. This can be useful to see if offset changes are happening in a single clock or all clocks together.

Clock Offset is field 5 in the peerstats log file.



Server Offset 130.207.244.240

peer offset 130.207.244.240 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 130.207.244.240 -836.192 -836.192 -616.795 -24.022 520.831 631.098 631.098 1,137.626 1,467.290 343.165 -85.693 µs -5.812 14.69

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 18.26.4.105

peer offset 18.26.4.105 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 18.26.4.105 -1.114 -1.114 -1.014 -0.424 0.238 0.391 0.391 1.252 1.506 0.359 -0.434 ms -17.16 53.48

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 192.5.41.41

peer offset 192.5.41.41 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.5.41.41 -2.591 -2.591 -2.371 0.083 0.871 1.124 1.124 3.242 3.715 1.217 -0.593 ms -8.067 21.42

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net)

peer offset 2001:470:0:2c8::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -1.163 -1.163 -1.036 -0.438 0.120 0.239 0.239 1.157 1.401 0.339 -0.452 ms -19.7 64.38

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net)

peer offset 2604:a880:2:d1::116:d001 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net) -1.746 -1.746 -1.511 -0.719 -0.329 -0.239 -0.239 1.182 1.507 0.378 -0.840 ms -43.86 181.6

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 2610:20:6f15:15::26 (time-e-g.nist.gov)

peer offset 2610:20:6f15:15::26 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2610:20:6f15:15::26 (time-e-g.nist.gov) -1.382 -1.382 -0.733 -0.165 0.402 0.800 0.800 1.135 2.182 0.354 -0.163 ms -7.929 24.89

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Jitters

peer jitters plot

The RMS Jitter of all refclocks and servers. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 130.207.244.240

peer jitter 130.207.244.240 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 130.207.244.240 45.356 45.356 57.231 128.198 827.151 948.771 948.771 769.920 903.415 229.899 228.107 µs 1.802 5.239

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 18.26.4.105

peer jitter 18.26.4.105 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 18.26.4.105 29.809 29.809 38.034 115.364 401.427 607.010 607.010 363.393 577.201 113.210 142.357 µs 2.797 9.963

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 192.5.41.41

peer jitter 192.5.41.41 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.5.41.41 0.043 0.043 0.057 0.154 0.922 2.019 2.019 0.865 1.976 0.383 0.266 ms 2.589 11.42

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net)

peer jitter 2001:470:0:2c8::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 20.522 20.522 29.065 87.595 252.908 321.201 321.201 223.843 300.679 60.746 103.640 µs 3.634 10.97

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net)

peer jitter 2604:a880:2:d1::116:d001 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net) 0.042 0.042 0.066 0.151 0.736 1.129 1.129 0.670 1.087 0.235 0.262 ms 1.84 5.48

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2610:20:6f15:15::26 (time-e-g.nist.gov)

peer jitter 2610:20:6f15:15::26 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2610:20:6f15:15::26 (time-e-g.nist.gov) 60.847 60.847 78.069 276.304 739.226 812.752 812.752 661.157 751.905 199.147 321.974 µs 2.745 6.487

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 21.187 21.187 21.203 21.340 21.602 21.637 21.637 0.399 0.450 0.141 21.384 ppm 3.392e+06 5.098e+08
Local Clock Time Offset -1.167 -1.167 -0.768 -0.112 0.340 0.641 0.641 1.108 1.808 0.352 -0.151 ms -7.707 22.81
Local RMS Frequency Jitter 13.086 13.086 15.564 22.467 38.881 43.682 43.682 23.317 30.596 7.268 24.330 ppb 20.9 75.09
Local RMS Time Jitter 128.896 128.896 135.681 195.680 250.799 300.292 300.292 115.118 171.396 37.727 194.077 µs 83.91 405.6
Server Jitter 130.207.244.240 45.356 45.356 57.231 128.198 827.151 948.771 948.771 769.920 903.415 229.899 228.107 µs 1.802 5.239
Server Jitter 18.26.4.105 29.809 29.809 38.034 115.364 401.427 607.010 607.010 363.393 577.201 113.210 142.357 µs 2.797 9.963
Server Jitter 192.5.41.41 0.043 0.043 0.057 0.154 0.922 2.019 2.019 0.865 1.976 0.383 0.266 ms 2.589 11.42
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 20.522 20.522 29.065 87.595 252.908 321.201 321.201 223.843 300.679 60.746 103.640 µs 3.634 10.97
Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net) 0.042 0.042 0.066 0.151 0.736 1.129 1.129 0.670 1.087 0.235 0.262 ms 1.84 5.48
Server Jitter 2610:20:6f15:15::26 (time-e-g.nist.gov) 60.847 60.847 78.069 276.304 739.226 812.752 812.752 661.157 751.905 199.147 321.974 µs 2.745 6.487
Server Offset 130.207.244.240 -836.192 -836.192 -616.795 -24.022 520.831 631.098 631.098 1,137.626 1,467.290 343.165 -85.693 µs -5.812 14.69
Server Offset 18.26.4.105 -1.114 -1.114 -1.014 -0.424 0.238 0.391 0.391 1.252 1.506 0.359 -0.434 ms -17.16 53.48
Server Offset 192.5.41.41 -2.591 -2.591 -2.371 0.083 0.871 1.124 1.124 3.242 3.715 1.217 -0.593 ms -8.067 21.42
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -1.163 -1.163 -1.036 -0.438 0.120 0.239 0.239 1.157 1.401 0.339 -0.452 ms -19.7 64.38
Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net) -1.746 -1.746 -1.511 -0.719 -0.329 -0.239 -0.239 1.182 1.507 0.378 -0.840 ms -43.86 181.6
Server Offset 2610:20:6f15:15::26 (time-e-g.nist.gov) -1.382 -1.382 -0.733 -0.165 0.402 0.800 0.800 1.135 2.182 0.354 -0.163 ms -7.929 24.89
Summary as CSV file

Glossary:

frequency offset:
The difference between the ntpd calculated frequency and the local system clock frequency (usually in parts per million, ppm)
jitter, dispersion:
The short term change in a value. NTP measures Local Time Jitter, Refclock Jitter, and Server Jitter in seconds. Local Frequency Jitter is in ppm or ppb.
kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses the Pearson's moment coefficient of kurtosis. A normal distribution has a kurtosis of three. NIST describes a kurtosis over three as "heavy tailed" and one under three as "light tailed".
ms, millisecond:
One thousandth of a second = 0.001 seconds, 1e-3 seconds
mu, mean:
The arithmetic mean: the sum of all the values divided by the number of values. The formula for mu is: "mu = (∑xi) / N". Where xi denotes the data points and N is the number of data points.
ns, nanosecond:
One billionth of a second, also one thousandth of a microsecond, 0.000000001 seconds and 1e-9 seconds.
percentile:
The value below which a given percentage of values fall.
ppb, parts per billion:
Ratio between two values. These following are all the same: 1 ppb, one in one billion, 1/1,000,000,000, 0.000,000,001, 1e-9 and 0.000,000,1%
ppm, parts per million:
Ratio between two values. These following are all the same: 1 ppm, one in one million, 1/1,000,000, 0.000,001, and 0.000,1%
‰, parts per thousand:
Ratio between two values. These following are all the same: 1 ‰. one in one thousand, 1/1,000, 0.001, and 0.1%
refclock:
Reference clock, a local GPS module or other local source of time.
remote clock:
Any clock reached over the network, LAN or WAN. Also called a peer or server.
time offset:
The difference between the ntpd calculated time and the local system clock's time. Also called phase offset.
σ, sigma:
Sigma denotes the standard deviation (SD) and is centered on the arithmetic mean of the data set. The SD is simply the square root of the variance of the data set. Two sigma is simply twice the standard deviation. Three sigma is three times sigma. Smaller is better.
The formula for sigma is: "σ = √[ ∑(xi-mu)^2 / N ]". Where xi denotes the data points and N is the number of data points.
skewness, Skew:
The skewness of a random variable X is the third standardized moment and is a dimension-less ratio. ntpviz uses the Pearson's moment coefficient of skewness. Wikipedia describes it best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
upstream clock:
Any server or reference clock used as a source of time.
µs, us, microsecond:
One millionth of a second, also one thousandth of a millisecond, 0.000,001 seconds, and 1e-6 seconds.



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