NTPsec

scratchy

Report generated: Thu Sep 18 07:15:02 2025 UTC
Start Time: Wed Sep 17 07:15:02 2025 UTC
End Time: Thu Sep 18 07:15:02 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 -373.000 -373.000 -292.967 -68.387 188.601 516.288 516.288 481.568 889.288 156.986 -57.019 µs -5.928 15.11
Local Clock Frequency Offset 21.883 21.883 21.904 22.089 22.197 22.221 22.221 0.293 0.338 0.079 22.081 ppm 2.16e+07 6.015e+09

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 77.800 77.800 80.498 112.257 192.254 218.931 218.931 111.756 141.131 33.123 121.374 µs 27.93 107.5

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 7.409 7.409 8.144 15.556 37.284 44.647 44.647 29.140 37.238 8.039 17.326 ppb 6.493 21.75

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 -373.000 -373.000 -292.967 -68.387 188.601 516.288 516.288 481.568 889.288 156.986 -57.019 µs -5.928 15.11

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 129.6.15.26

peer offset 129.6.15.26 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 129.6.15.26 -589.306 -589.306 -487.272 -287.345 -0.455 53.163 53.163 486.817 642.469 156.819 -269.269 µs -28.01 99.01

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 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 -307.053 -307.053 -277.373 -1.239 321.860 489.811 489.811 599.233 796.864 161.160 18.505 µs -3.016 7.286

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 -404.352 -404.352 -314.160 -76.324 266.211 280.712 280.712 580.371 685.064 155.276 -63.672 µs -6.666 16.69

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 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 192.5.41.41 140.502 140.502 229.711 474.178 779.892 979.332 979.332 550.181 838.830 157.911 500.398 µs 17.2 58.33

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) -0.878 -0.878 -0.808 0.032 0.733 1.665 1.665 1.541 2.543 0.476 0.092 ms -2.278 6.801

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) -884.539 -884.539 -655.850 -35.087 385.213 588.263 588.263 1,041.063 1,472.802 349.902 -110.229 µs -6.422 16.46

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 129.6.15.26

peer jitter 129.6.15.26 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 129.6.15.26 25.811 25.811 34.300 92.843 187.315 230.748 230.748 153.015 204.937 51.122 102.111 µs 4.545 11.58

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 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 29.582 29.582 33.710 87.958 455.257 897.169 897.169 421.547 867.587 143.944 130.503 µs 3.256 15.41

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 33.459 33.459 38.956 131.198 324.455 403.873 403.873 285.499 370.414 88.677 148.991 µs 3.233 8.61

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 43.872 43.872 49.071 111.901 241.844 340.271 340.271 192.773 296.399 64.301 123.473 µs 4.492 12.88

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) 0.015 0.015 0.030 0.126 1.917 2.197 2.197 1.887 2.182 0.549 0.340 ms 1.062 4.089

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) 28.972 28.972 46.444 123.260 449.199 929.389 929.389 402.755 900.417 161.193 168.250 µs 3.132 13.24

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 21.883 21.883 21.904 22.089 22.197 22.221 22.221 0.293 0.338 0.079 22.081 ppm 2.16e+07 6.015e+09
Local Clock Time Offset -373.000 -373.000 -292.967 -68.387 188.601 516.288 516.288 481.568 889.288 156.986 -57.019 µs -5.928 15.11
Local RMS Frequency Jitter 7.409 7.409 8.144 15.556 37.284 44.647 44.647 29.140 37.238 8.039 17.326 ppb 6.493 21.75
Local RMS Time Jitter 77.800 77.800 80.498 112.257 192.254 218.931 218.931 111.756 141.131 33.123 121.374 µs 27.93 107.5
Server Jitter 129.6.15.26 25.811 25.811 34.300 92.843 187.315 230.748 230.748 153.015 204.937 51.122 102.111 µs 4.545 11.58
Server Jitter 130.207.244.240 29.582 29.582 33.710 87.958 455.257 897.169 897.169 421.547 867.587 143.944 130.503 µs 3.256 15.41
Server Jitter 18.26.4.105 33.459 33.459 38.956 131.198 324.455 403.873 403.873 285.499 370.414 88.677 148.991 µs 3.233 8.61
Server Jitter 192.5.41.41 43.872 43.872 49.071 111.901 241.844 340.271 340.271 192.773 296.399 64.301 123.473 µs 4.492 12.88
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 0.015 0.015 0.030 0.126 1.917 2.197 2.197 1.887 2.182 0.549 0.340 ms 1.062 4.089
Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net) 28.972 28.972 46.444 123.260 449.199 929.389 929.389 402.755 900.417 161.193 168.250 µs 3.132 13.24
Server Offset 129.6.15.26 -589.306 -589.306 -487.272 -287.345 -0.455 53.163 53.163 486.817 642.469 156.819 -269.269 µs -28.01 99.01
Server Offset 130.207.244.240 -307.053 -307.053 -277.373 -1.239 321.860 489.811 489.811 599.233 796.864 161.160 18.505 µs -3.016 7.286
Server Offset 18.26.4.105 -404.352 -404.352 -314.160 -76.324 266.211 280.712 280.712 580.371 685.064 155.276 -63.672 µs -6.666 16.69
Server Offset 192.5.41.41 140.502 140.502 229.711 474.178 779.892 979.332 979.332 550.181 838.830 157.911 500.398 µs 17.2 58.33
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -0.878 -0.878 -0.808 0.032 0.733 1.665 1.665 1.541 2.543 0.476 0.092 ms -2.278 6.801
Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net) -884.539 -884.539 -655.850 -35.087 385.213 588.263 588.263 1,041.063 1,472.802 349.902 -110.229 µs -6.422 16.46
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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