NTPsec

ntp2.sebi.org

Report generated: Mon Apr 13 21:45:01 2026 UTC
Start Time: Mon Apr 6 21:45:01 2026 UTC
End Time: Mon Apr 13 21:45:01 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 -22.192 -17.869 -9.288 0.008 0.426 45.798 56.482 9.713 63.667 7.246 -0.162 ms 4.802 40.17
Local Clock Frequency Offset -9.438 -9.424 -9.301 -9.199 -7.215 0.472 8.521 2.085 9.896 1.947 -8.760 ppm 5.632 38.68

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 0.000 0.013 0.053 0.148 11.068 19.526 25.327 11.015 19.513 3.892 1.345 ms 3.715 16.72

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 0.0000 0.0000 0.0014 0.0111 1.448 4.707 6.269 1.447 4.707 0.784 0.215 ppm 5.045 30.48

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 -22.192 -17.869 -9.288 0.008 0.426 45.798 56.482 9.713 63.667 7.246 -0.162 ms 4.802 40.17

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 -0.022 -0.018 -0.007 0.000 0.011 1.124 1.124 0.019 1.142 0.157 0.028 s 5.789 36.2

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 -23.436 -17.179 -7.455 0.153 0.857 845.851 1,124.202 8.312 863.030 127.005 17.757 ms 7.508 60.28

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 192.171.1.150

peer offset 192.171.1.150 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.171.1.150 -28.680 -19.267 -10.604 0.137 3.530 845.968 1,124.211 14.134 865.236 122.980 16.742 ms 7.431 59.42

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 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 -23.662 -18.247 -8.682 -0.434 0.225 845.213 1,123.608 8.906 863.460 120.007 15.441 ms 7.799 64.86

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) -21.690 -16.730 -7.193 0.103 0.757 845.775 1,124.163 7.950 862.505 136.247 20.349 ms 6.905 50.75

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) -22.199 -16.917 -7.097 -0.032 0.451 627.035 845.634 7.548 643.952 90.165 10.520 ms 8.568 75.89

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 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) -21.845 -16.832 -7.560 -0.002 0.460 845.558 845.582 8.020 862.390 88.730 9.462 ms 9.256 87.22

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 0.000 0.000 0.021 0.164 5.138 9.899 56.747 5.117 9.899 4.708 1.092 ms 9.367 99.59

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 0.000 0.000 0.042 0.185 2.687 11.099 54.439 2.645 11.099 4.559 0.916 ms 9.89 106.9

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 192.171.1.150

peer jitter 192.171.1.150 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.171.1.150 0.000 0.000 0.075 3.709 10.474 30.298 57.833 10.399 30.298 5.479 4.290 ms 5.195 44.34

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 0.000 0.000 0.023 0.152 3.368 17.340 56.062 3.345 17.340 4.645 0.908 ms 9.772 105

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) 0.000 0.000 0.016 0.148 2.795 10.176 55.513 2.779 10.176 4.588 0.856 ms 10.12 110.8

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) 0.000 0.000 0.013 0.172 3.789 29.561 56.741 3.776 29.561 4.802 1.073 ms 9.194 93.92

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) 0.000 0.000 0.014 0.162 3.506 28.800 57.073 3.492 28.800 4.835 0.942 ms 9.414 95.89

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 -9.438 -9.424 -9.301 -9.199 -7.215 0.472 8.521 2.085 9.896 1.947 -8.760 ppm 5.632 38.68
Local Clock Time Offset -22.192 -17.869 -9.288 0.008 0.426 45.798 56.482 9.713 63.667 7.246 -0.162 ms 4.802 40.17
Local RMS Frequency Jitter 0.0000 0.0000 0.0014 0.0111 1.448 4.707 6.269 1.447 4.707 0.784 0.215 ppm 5.045 30.48
Local RMS Time Jitter 0.000 0.013 0.053 0.148 11.068 19.526 25.327 11.015 19.513 3.892 1.345 ms 3.715 16.72
Server Jitter 131.188.3.221 0.000 0.000 0.021 0.164 5.138 9.899 56.747 5.117 9.899 4.708 1.092 ms 9.367 99.59
Server Jitter 185.131.196.23 0.000 0.000 0.042 0.185 2.687 11.099 54.439 2.645 11.099 4.559 0.916 ms 9.89 106.9
Server Jitter 192.171.1.150 0.000 0.000 0.075 3.709 10.474 30.298 57.833 10.399 30.298 5.479 4.290 ms 5.195 44.34
Server Jitter 193.79.237.14 0.000 0.000 0.023 0.152 3.368 17.340 56.062 3.345 17.340 4.645 0.908 ms 9.772 105
Server Jitter 2001:628:2030:dcf1::ac0 (ts1.aco.net) 0.000 0.000 0.016 0.148 2.795 10.176 55.513 2.779 10.176 4.588 0.856 ms 10.12 110.8
Server Jitter 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) 0.000 0.000 0.013 0.172 3.789 29.561 56.741 3.776 29.561 4.802 1.073 ms 9.194 93.92
Server Jitter 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) 0.000 0.000 0.014 0.162 3.506 28.800 57.073 3.492 28.800 4.835 0.942 ms 9.414 95.89
Server Offset 131.188.3.221 -0.022 -0.018 -0.007 0.000 0.011 1.124 1.124 0.019 1.142 0.157 0.028 s 5.789 36.2
Server Offset 185.131.196.23 -23.436 -17.179 -7.455 0.153 0.857 845.851 1,124.202 8.312 863.030 127.005 17.757 ms 7.508 60.28
Server Offset 192.171.1.150 -28.680 -19.267 -10.604 0.137 3.530 845.968 1,124.211 14.134 865.236 122.980 16.742 ms 7.431 59.42
Server Offset 193.79.237.14 -23.662 -18.247 -8.682 -0.434 0.225 845.213 1,123.608 8.906 863.460 120.007 15.441 ms 7.799 64.86
Server Offset 2001:628:2030:dcf1::ac0 (ts1.aco.net) -21.690 -16.730 -7.193 0.103 0.757 845.775 1,124.163 7.950 862.505 136.247 20.349 ms 6.905 50.75
Server Offset 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) -22.199 -16.917 -7.097 -0.032 0.451 627.035 845.634 7.548 643.952 90.165 10.520 ms 8.568 75.89
Server Offset 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) -21.845 -16.832 -7.560 -0.002 0.460 845.558 845.582 8.020 862.390 88.730 9.462 ms 9.256 87.22
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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