NTPsec

ntp2.sebi.org

Report generated: Sat Aug 22 09:45:03 2026 UTC
Start Time: Sat Aug 15 09:45:03 2026 UTC
End Time: Sat Aug 22 09:45:03 2026 UTC
Report Period: 7.0 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 -944.526 -655.898 -305.509 29.260 435.094 778.710 1,054.166 740.603 1,434.608 232.629 40.933 µs 0.09101 6.107
Local Clock Frequency Offset 49.644 49.655 49.661 50.116 50.314 50.352 50.362 0.653 0.697 0.191 50.072 ppm -0.8854 2.873

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 22.840 26.376 35.800 64.596 696.677 771.030 784.715 660.877 744.654 175.450 123.339 µs 2.831 9.66

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 1.420 1.519 1.819 10.193 24.978 29.405 33.925 23.159 27.886 6.509 11.174 ppb 0.8511 3.634

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 -944.526 -655.898 -305.509 29.260 435.094 778.710 1,054.166 740.603 1,434.608 232.629 40.933 µs 0.09101 6.107

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 -2.772 -0.606 -0.241 0.073 0.617 1.076 1.439 0.857 1.681 0.299 0.102 ms -1.228 26.36

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 -0.433 -0.247 0.029 0.317 0.790 1.689 5.157 0.762 1.936 0.408 0.368 ms 6.854 72.79

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 -626.328 -466.711 -126.575 147.617 472.834 695.744 999.718 599.409 1,162.455 199.300 159.212 µs 0.1033 6.411

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 -1.826 -1.522 -1.032 -0.021 0.256 0.387 0.517 1.288 1.909 0.356 -0.087 ms -2.508 10.15

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) -2,358.683 -738.975 -335.541 -26.265 319.284 569.389 960.337 654.825 1,308.364 266.765 -23.398 µs -3.107 30.78

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) -3,160.421 -616.319 -305.515 30.870 340.650 514.469 885.772 646.165 1,130.788 254.725 17.547 µs -4.829 62.12

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) -1.411 -1.016 -0.436 0.072 0.913 1.376 1.854 1.350 2.392 0.404 0.106 ms 0.5834 5.96

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 0.008 0.012 0.019 0.078 0.396 1.585 3.503 0.377 1.572 0.290 0.148 ms 6.312 55.53

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 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 0.016 0.026 0.038 0.105 2.447 5.888 7.170 2.409 5.862 1.028 0.392 ms 4.57 25.58

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 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 17.820 23.118 28.994 77.672 257.682 375.679 502.017 228.688 352.561 77.809 105.104 µs 1.755 6.887

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 0.011 0.014 0.020 0.070 0.391 8.017 8.184 0.371 8.003 1.030 0.254 ms 7.112 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) 0.008 0.016 0.021 0.078 0.287 1.697 2.200 0.266 1.682 0.234 0.129 ms 6.47 49.84

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) 0.010 0.018 0.025 0.081 0.280 1.315 3.335 0.255 1.296 0.220 0.130 ms 9.516 122.2

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) 0.009 0.017 0.030 0.179 0.844 1.305 1.409 0.814 1.288 0.275 0.271 ms 1.827 6.271

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 49.644 49.655 49.661 50.116 50.314 50.352 50.362 0.653 0.697 0.191 50.072 ppm -0.8854 2.873
Local Clock Time Offset -944.526 -655.898 -305.509 29.260 435.094 778.710 1,054.166 740.603 1,434.608 232.629 40.933 µs 0.09101 6.107
Local RMS Frequency Jitter 1.420 1.519 1.819 10.193 24.978 29.405 33.925 23.159 27.886 6.509 11.174 ppb 0.8511 3.634
Local RMS Time Jitter 22.840 26.376 35.800 64.596 696.677 771.030 784.715 660.877 744.654 175.450 123.339 µs 2.831 9.66
Server Jitter 131.188.3.221 0.008 0.012 0.019 0.078 0.396 1.585 3.503 0.377 1.572 0.290 0.148 ms 6.312 55.53
Server Jitter 185.131.196.23 0.016 0.026 0.038 0.105 2.447 5.888 7.170 2.409 5.862 1.028 0.392 ms 4.57 25.58
Server Jitter 192.53.103.104 17.820 23.118 28.994 77.672 257.682 375.679 502.017 228.688 352.561 77.809 105.104 µs 1.755 6.887
Server Jitter 193.79.237.14 0.011 0.014 0.020 0.070 0.391 8.017 8.184 0.371 8.003 1.030 0.254 ms 7.112 53
Server Jitter 2001:628:2030:dcf1::ac0 (ts1.aco.net) 0.008 0.016 0.021 0.078 0.287 1.697 2.200 0.266 1.682 0.234 0.129 ms 6.47 49.84
Server Jitter 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) 0.010 0.018 0.025 0.081 0.280 1.315 3.335 0.255 1.296 0.220 0.130 ms 9.516 122.2
Server Jitter 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) 0.009 0.017 0.030 0.179 0.844 1.305 1.409 0.814 1.288 0.275 0.271 ms 1.827 6.271
Server Offset 131.188.3.221 -2.772 -0.606 -0.241 0.073 0.617 1.076 1.439 0.857 1.681 0.299 0.102 ms -1.228 26.36
Server Offset 185.131.196.23 -0.433 -0.247 0.029 0.317 0.790 1.689 5.157 0.762 1.936 0.408 0.368 ms 6.854 72.79
Server Offset 192.53.103.104 -626.328 -466.711 -126.575 147.617 472.834 695.744 999.718 599.409 1,162.455 199.300 159.212 µs 0.1033 6.411
Server Offset 193.79.237.14 -1.826 -1.522 -1.032 -0.021 0.256 0.387 0.517 1.288 1.909 0.356 -0.087 ms -2.508 10.15
Server Offset 2001:628:2030:dcf1::ac0 (ts1.aco.net) -2,358.683 -738.975 -335.541 -26.265 319.284 569.389 960.337 654.825 1,308.364 266.765 -23.398 µs -3.107 30.78
Server Offset 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) -3,160.421 -616.319 -305.515 30.870 340.650 514.469 885.772 646.165 1,130.788 254.725 17.547 µs -4.829 62.12
Server Offset 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) -1.411 -1.016 -0.436 0.072 0.913 1.376 1.854 1.350 2.392 0.404 0.106 ms 0.5834 5.96
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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