NTPsec

ntp2.sebi.org

Report generated: Fri Oct 23 21:53:04 2026 UTC
Start Time: Thu Oct 22 21:53:04 2026 UTC
End Time: Fri Oct 23 21:53:04 2026 UTC
Report Period: 1.0 days

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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 -1.281 -1.281 -0.166 -0.010 0.228 0.273 0.273 0.394 1.554 0.198 0.000 ms -3.872 26.44
Local Clock Frequency Offset 49.043 49.043 49.043 49.063 49.132 49.134 49.134 0.089 0.091 0.024 49.070 ppm 1.228 3.895

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 40.348 40.348 45.382 89.057 462.000 564.416 564.416 416.618 524.068 138.735 161.858 µs 1.221 3.446

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 2.485 2.485 3.013 6.546 13.467 15.313 15.313 10.454 12.828 3.535 7.625 ppb 0.4081 1.834

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 -1.281 -1.281 -0.166 -0.010 0.228 0.273 0.273 0.394 1.554 0.198 0.000 ms -3.872 26.44

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 131.188.3.221

peer offset 131.188.3.221 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 131.188.3.221 -3.238 -3.238 -0.172 0.054 0.290 1.921 1.921 0.462 5.159 0.548 0.013 ms -3.254 26.7

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 185.131.196.23

peer offset 185.131.196.23 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 185.131.196.23 37.267 37.267 60.137 260.399 525.665 588.175 588.175 465.528 550.908 130.737 274.625 µs 0.4195 2.707

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 192.53.103.104

peer offset 192.53.103.104 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.53.103.104 -231.093 -231.093 -224.174 -32.268 253.192 277.972 277.972 477.366 509.065 133.719 -3.801 µs 0.4423 2.359

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 193.79.237.14

peer offset 193.79.237.14 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 193.79.237.14 -244.367 -244.367 -211.428 4.898 256.208 262.630 262.630 467.636 506.997 125.833 11.250 µs 0.2191 2.573

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 2001:628:2030:dcf1::ac0 (ts1.aco.net)

peer offset 2001:628:2030:dcf1::ac0 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:628:2030:dcf1::ac0 (ts1.aco.net) -286.908 -286.908 -258.037 -33.032 222.351 257.480 257.480 480.388 544.388 128.689 -18.440 µs 0.1456 2.656

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 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de)

peer offset 2001:638:a000:1123:123::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) -3.172 -3.172 -1.195 -0.030 0.216 0.276 0.276 1.411 3.448 0.512 -0.119 ms -4.415 24.57

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 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de)

peer offset 2a01:4f8:0:a112::2:2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) -189.973 -189.973 -179.150 67.499 265.342 341.925 341.925 444.492 531.898 143.593 51.393 µs -0.04666 2.08

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 131.188.3.221

peer jitter 131.188.3.221 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 131.188.3.221 0.018 0.018 0.026 0.074 1.972 3.287 3.287 1.947 3.270 0.787 0.528 ms 1.747 5.662

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 185.131.196.23

peer jitter 185.131.196.23 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 185.131.196.23 25.452 25.452 35.420 102.600 247.331 294.309 294.309 211.911 268.857 61.728 113.854 µs 0.9898 3.4

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 192.53.103.104

peer jitter 192.53.103.104 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.53.103.104 0.028 0.028 0.032 0.089 1.319 1.323 1.323 1.287 1.295 0.383 0.244 ms 2.168 6.096

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 193.79.237.14

peer jitter 193.79.237.14 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 193.79.237.14 17.338 17.338 20.885 73.208 201.893 249.648 249.648 181.008 232.310 54.569 85.347 µs 1.09 3.53

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 2001:628:2030:dcf1::ac0 (ts1.aco.net)

peer jitter 2001:628:2030:dcf1::ac0 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:628:2030:dcf1::ac0 (ts1.aco.net) 13.608 13.608 18.026 58.965 191.478 224.641 224.641 173.452 211.033 55.723 81.161 µs 0.9875 2.731

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 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de)

peer jitter 2001:638:a000:1123:123::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) 0.017 0.017 0.024 0.068 1.895 2.627 2.627 1.871 2.610 0.643 0.453 ms 1.501 4.308

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 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de)

peer jitter 2a01:4f8:0:a112::2:2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) 27.431 27.431 41.414 117.440 217.121 242.962 242.962 175.707 215.531 52.107 116.470 µs 0.4168 2.448

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 49.043 49.043 49.043 49.063 49.132 49.134 49.134 0.089 0.091 0.024 49.070 ppm 1.228 3.895
Local Clock Time Offset -1.281 -1.281 -0.166 -0.010 0.228 0.273 0.273 0.394 1.554 0.198 0.000 ms -3.872 26.44
Local RMS Frequency Jitter 2.485 2.485 3.013 6.546 13.467 15.313 15.313 10.454 12.828 3.535 7.625 ppb 0.4081 1.834
Local RMS Time Jitter 40.348 40.348 45.382 89.057 462.000 564.416 564.416 416.618 524.068 138.735 161.858 µs 1.221 3.446
Server Jitter 131.188.3.221 0.018 0.018 0.026 0.074 1.972 3.287 3.287 1.947 3.270 0.787 0.528 ms 1.747 5.662
Server Jitter 185.131.196.23 25.452 25.452 35.420 102.600 247.331 294.309 294.309 211.911 268.857 61.728 113.854 µs 0.9898 3.4
Server Jitter 192.53.103.104 0.028 0.028 0.032 0.089 1.319 1.323 1.323 1.287 1.295 0.383 0.244 ms 2.168 6.096
Server Jitter 193.79.237.14 17.338 17.338 20.885 73.208 201.893 249.648 249.648 181.008 232.310 54.569 85.347 µs 1.09 3.53
Server Jitter 2001:628:2030:dcf1::ac0 (ts1.aco.net) 13.608 13.608 18.026 58.965 191.478 224.641 224.641 173.452 211.033 55.723 81.161 µs 0.9875 2.731
Server Jitter 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) 0.017 0.017 0.024 0.068 1.895 2.627 2.627 1.871 2.610 0.643 0.453 ms 1.501 4.308
Server Jitter 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) 27.431 27.431 41.414 117.440 217.121 242.962 242.962 175.707 215.531 52.107 116.470 µs 0.4168 2.448
Server Offset 131.188.3.221 -3.238 -3.238 -0.172 0.054 0.290 1.921 1.921 0.462 5.159 0.548 0.013 ms -3.254 26.7
Server Offset 185.131.196.23 37.267 37.267 60.137 260.399 525.665 588.175 588.175 465.528 550.908 130.737 274.625 µs 0.4195 2.707
Server Offset 192.53.103.104 -231.093 -231.093 -224.174 -32.268 253.192 277.972 277.972 477.366 509.065 133.719 -3.801 µs 0.4423 2.359
Server Offset 193.79.237.14 -244.367 -244.367 -211.428 4.898 256.208 262.630 262.630 467.636 506.997 125.833 11.250 µs 0.2191 2.573
Server Offset 2001:628:2030:dcf1::ac0 (ts1.aco.net) -286.908 -286.908 -258.037 -33.032 222.351 257.480 257.480 480.388 544.388 128.689 -18.440 µs 0.1456 2.656
Server Offset 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) -3.172 -3.172 -1.195 -0.030 0.216 0.276 0.276 1.411 3.448 0.512 -0.119 ms -4.415 24.57
Server Offset 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) -189.973 -189.973 -179.150 67.499 265.342 341.925 341.925 444.492 531.898 143.593 51.393 µs -0.04666 2.08
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.
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 FIsher-Pearson moment of skewness. There are other different ways to calculate Skewness Wikipedia describes Skewness best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
Kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses standard Kurtosis. There are other different ways to calculate 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".
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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