NTPsec

ntp2.sebi.org

Report generated: Sat Aug 22 19:53:03 2026 UTC
Start Time: Fri Aug 21 19:53:03 2026 UTC
End Time: Sat Aug 22 19:53:03 2026 UTC
Report Period: 1.0 days

Top   Daily Stats   Weekly Stats  

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 -369.095 -369.095 -272.891 -41.085 165.834 234.384 234.384 438.725 603.479 122.984 -26.146 µs -0.4362 3.871
Local Clock Frequency Offset 49.930 49.930 49.942 50.076 50.095 50.095 50.095 0.153 0.165 0.044 50.057 ppm -1.79 4.976

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 36.989 36.989 40.829 63.580 77.544 80.766 80.766 36.715 43.777 11.422 60.688 µs -0.3594 2.202

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 2.500 2.500 2.754 4.630 13.659 15.689 15.689 10.905 13.189 3.492 6.006 ppb 1.299 3.543

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 -369.095 -369.095 -272.891 -41.085 165.834 234.384 234.384 438.725 603.479 122.984 -26.146 µs -0.4362 3.871

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 -342.748 -342.748 -266.037 3.560 179.653 188.055 188.055 445.690 530.803 104.317 0.333 µs -1.018 5.232

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 -99.197 -99.197 -6.221 259.417 409.536 441.556 441.556 415.757 540.753 114.940 246.852 µs -1.086 4.129

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 -211.674 -211.674 -157.856 99.104 276.829 281.580 281.580 434.685 493.254 109.933 83.560 µs -0.5934 3.735

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 -387.535 -387.535 -316.037 -74.244 116.071 120.501 120.501 432.108 508.036 98.300 -81.905 µs -0.6787 4.676

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) -371.546 -371.546 -333.398 -74.535 89.475 114.289 114.289 422.873 485.835 104.281 -79.985 µs -0.7014 4.082

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) -380.742 -380.742 -325.659 -39.488 122.342 137.580 137.580 448.001 518.322 116.143 -45.715 µs -0.7955 3.81

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) -763.402 -763.402 -589.983 33.812 474.587 532.848 532.848 1,064.570 1,296.250 284.322 57.917 µs -0.5837 3.946

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 7.866 7.866 17.406 40.078 152.039 166.574 166.574 134.633 158.708 39.064 53.988 µs 1.375 4.047

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 31.333 31.333 33.627 77.313 185.577 233.682 233.682 151.950 202.349 53.204 96.145 µs 0.8172 2.675

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 14.289 14.289 17.820 49.607 164.910 206.164 206.164 147.090 191.875 42.316 65.397 µs 1.18 4.045

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 11.143 11.143 14.610 46.741 153.322 157.137 157.137 138.712 145.994 40.461 58.566 µs 1.07 3.053

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) 16.174 16.174 18.898 36.110 151.125 164.301 164.301 132.227 148.127 41.382 56.449 µs 1.24 3.356

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) 10.138 10.138 18.152 75.056 164.927 183.618 183.618 146.775 173.480 39.608 76.654 µs 0.6694 3.249

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) 12.562 12.562 19.207 166.855 585.007 626.219 626.219 565.800 613.657 167.276 202.107 µs 1.081 3.256

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 49.930 49.930 49.942 50.076 50.095 50.095 50.095 0.153 0.165 0.044 50.057 ppm -1.79 4.976
Local Clock Time Offset -369.095 -369.095 -272.891 -41.085 165.834 234.384 234.384 438.725 603.479 122.984 -26.146 µs -0.4362 3.871
Local RMS Frequency Jitter 2.500 2.500 2.754 4.630 13.659 15.689 15.689 10.905 13.189 3.492 6.006 ppb 1.299 3.543
Local RMS Time Jitter 36.989 36.989 40.829 63.580 77.544 80.766 80.766 36.715 43.777 11.422 60.688 µs -0.3594 2.202
Server Jitter 131.188.3.221 7.866 7.866 17.406 40.078 152.039 166.574 166.574 134.633 158.708 39.064 53.988 µs 1.375 4.047
Server Jitter 185.131.196.23 31.333 31.333 33.627 77.313 185.577 233.682 233.682 151.950 202.349 53.204 96.145 µs 0.8172 2.675
Server Jitter 192.53.103.104 14.289 14.289 17.820 49.607 164.910 206.164 206.164 147.090 191.875 42.316 65.397 µs 1.18 4.045
Server Jitter 193.79.237.14 11.143 11.143 14.610 46.741 153.322 157.137 157.137 138.712 145.994 40.461 58.566 µs 1.07 3.053
Server Jitter 2001:628:2030:dcf1::ac0 (ts1.aco.net) 16.174 16.174 18.898 36.110 151.125 164.301 164.301 132.227 148.127 41.382 56.449 µs 1.24 3.356
Server Jitter 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) 10.138 10.138 18.152 75.056 164.927 183.618 183.618 146.775 173.480 39.608 76.654 µs 0.6694 3.249
Server Jitter 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) 12.562 12.562 19.207 166.855 585.007 626.219 626.219 565.800 613.657 167.276 202.107 µs 1.081 3.256
Server Offset 131.188.3.221 -342.748 -342.748 -266.037 3.560 179.653 188.055 188.055 445.690 530.803 104.317 0.333 µs -1.018 5.232
Server Offset 185.131.196.23 -99.197 -99.197 -6.221 259.417 409.536 441.556 441.556 415.757 540.753 114.940 246.852 µs -1.086 4.129
Server Offset 192.53.103.104 -211.674 -211.674 -157.856 99.104 276.829 281.580 281.580 434.685 493.254 109.933 83.560 µs -0.5934 3.735
Server Offset 193.79.237.14 -387.535 -387.535 -316.037 -74.244 116.071 120.501 120.501 432.108 508.036 98.300 -81.905 µs -0.6787 4.676
Server Offset 2001:628:2030:dcf1::ac0 (ts1.aco.net) -371.546 -371.546 -333.398 -74.535 89.475 114.289 114.289 422.873 485.835 104.281 -79.985 µs -0.7014 4.082
Server Offset 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) -380.742 -380.742 -325.659 -39.488 122.342 137.580 137.580 448.001 518.322 116.143 -45.715 µs -0.7955 3.81
Server Offset 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) -763.402 -763.402 -589.983 33.812 474.587 532.848 532.848 1,064.570 1,296.250 284.322 57.917 µs -0.5837 3.946
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.



This page autogenerated by ntpviz, part of the NTPsec project
html 5    Valid CSS!