NTPsec

A-ntpsec-72-hour-stats

Report generated: Thu Sep 29 13:13:15 2022 UTC
Start Time: Mon Sep 26 13:13:13 2022 UTC
End Time: Thu Sep 29 13:13:13 2022 UTC
Report published: Thu Sep 29 06:13:29 2022 PDT
Report Period: 3.0 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 -5.921 -1.355 -0.929 0.032 0.814 1.183 2.805 1.743 2.538 0.531 -0.000 µs -4.31 12.09
Local Clock Frequency Offset -116.776 -112.823 -102.676 -44.922 2.945 8.728 13.596 105.621 121.551 32.892 -47.049 ppb -21.83 74.1

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 0.263 0.383 0.450 0.675 1.005 1.182 2.793 0.555 0.799 0.172 0.695 µs 38.24 159.1

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 110.000 146.000 170.000 247.000 357.000 414.000 1,076.000 187.000 268.000 58.262 253.044 10e-12 48.45 214.7

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 -5.921 -1.355 -0.929 0.032 0.814 1.183 2.805 1.743 2.538 0.531 -0.000 µs -4.31 12.09

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats log file.



Local Temperatures

local temps plot

Local temperatures. These will be site-specific depending upon what temperature sensors you collect data from. Temperature changes affect the local clock crystal frequency and stability. The math of how temperature changes frequency is complex, and also depends on crystal aging. So there is no easy way to correct for it in software. This is the single most important component of frequency drift.

The Local Temperatures are from field 3 from the tempstats log file.



Local Frequency/Temp

local freq temps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -116.776 -112.823 -102.676 -44.922 2.945 8.728 13.596 105.621 121.551 32.892 -47.049 ppb -21.83 74.1
Temp ZONE0 49.926 50.464 51.002 52.078 53.692 53.692 54.230 2.690 3.228 0.866 52.315 °C

The frequency offsets and temperatures. Showing frequency offset (red, in parts per million, scale on right) and the temperatures.

These are field 4 (frequency) from the loopstats log file, and field 3 from the tempstats log file.



Local GPS

local gps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
nSats 6.000 7.000 8.000 10.000 11.000 12.000 13.000 3.000 5.000 1.112 9.569 nSat 462.1 3691
TDOP 0.500 0.520 0.580 0.830 1.280 1.540 2.110 0.700 1.020 0.213 0.855 37.64 156.3

Local GPS. The Time Dilution of Precision (TDOP) is plotted in blue. The number of visible satellites (nSat) is plotted in red.

TDOP is field 3, and nSats is field 4, from the gpsd log file. The gpsd log file is created by the ntploggps program.

TDOP is a dimensionless error factor. Smaller numbers are better. TDOP ranges from 1 (ideal), 2 to 5 (good), to greater than 20 (poor). Some GNSS receivers report TDOP less than one which is theoretically impossible.



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 169.229.128.134

peer offset 169.229.128.134 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 169.229.128.134 1.898 2.135 2.306 2.696 3.126 3.333 4.324 0.820 1.198 0.255 2.700 ms 912.2 9049

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 173.11.101.155

peer offset 173.11.101.155 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 173.11.101.155 -2.661 -1.937 -1.359 -0.161 0.769 1.476 4.407 2.128 3.414 0.662 -0.207 ms -6.047 19.06

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 192.168.1.11

peer offset 192.168.1.11 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.168.1.11 -517.448 -268.010 -166.171 16.269 283.446 347.021 625.488 449.617 615.031 141.109 31.537 µs -2.552 5.944

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 209.50.50.228

peer offset 209.50.50.228 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 209.50.50.228 -1.029 -0.577 -0.313 3.516 4.049 4.320 4.950 4.362 4.898 1.244 3.115 ms 5.736 11.99

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 216.218.254.202

peer offset 216.218.254.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 216.218.254.202 0.149 1.910 2.160 2.629 3.073 3.310 4.078 0.913 1.401 0.298 2.621 ms 498.4 4069

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 66.220.9.122

peer offset 66.220.9.122 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 66.220.9.122 1.344 1.831 2.066 2.489 2.923 3.181 3.529 0.857 1.350 0.268 2.485 ms 592.9 5122

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 SHM(0)

peer offset SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(0) -134.808 -133.849 -132.538 -130.075 -128.220 -126.984 -125.098 4.318 6.865 1.345 -130.177 ms -9.357e+05 9.154e+07

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 SHM(1)

peer offset SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(1) -5.922 -1.356 -0.930 0.033 0.815 1.184 2.806 1.745 2.540 0.532 -0.000 µs -4.309 12.07

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 169.229.128.134

peer jitter 169.229.128.134 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 169.229.128.134 0.139 0.245 0.388 1.025 9.955 14.933 24.965 9.568 14.688 3.131 2.052 ms 2.459 13.42

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 173.11.101.155

peer jitter 173.11.101.155 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 173.11.101.155 0.350 0.677 0.968 1.956 9.937 22.104 53.628 8.969 21.427 4.164 3.147 ms 5.158 51.2

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 192.168.1.11

peer jitter 192.168.1.11 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.168.1.11 0.047 0.102 0.143 0.322 2.405 11.277 22.150 2.261 11.175 1.874 0.740 ms 4.067 33.18

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 209.50.50.228

peer jitter 209.50.50.228 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 209.50.50.228 0.203 0.299 0.406 1.054 10.554 14.394 21.340 10.148 14.094 3.183 2.197 ms 1.915 8.566

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 216.218.254.202

peer jitter 216.218.254.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 216.218.254.202 0.168 0.257 0.392 1.115 10.082 15.359 22.296 9.690 15.102 3.189 2.151 ms 2.202 10.48

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 66.220.9.122

peer jitter 66.220.9.122 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 66.220.9.122 0.186 0.262 0.388 1.133 10.575 16.633 25.227 10.187 16.371 3.423 2.209 ms 2.39 12.27

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 SHM(0)

peer jitter SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter SHM(0) 0.027 0.066 0.098 0.285 0.901 1.290 2.777 0.804 1.224 0.266 0.367 ms 2.866 10.15

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 SHM(1)

peer jitter SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter SHM(1) 0.102 0.240 0.324 0.646 1.270 1.653 6.020 0.946 1.413 0.300 0.702 µs 7.832 30.16

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 -116.776 -112.823 -102.676 -44.922 2.945 8.728 13.596 105.621 121.551 32.892 -47.049 ppb -21.83 74.1
Local Clock Time Offset -5.921 -1.355 -0.929 0.032 0.814 1.183 2.805 1.743 2.538 0.531 -0.000 µs -4.31 12.09
Local RMS Frequency Jitter 110.000 146.000 170.000 247.000 357.000 414.000 1,076.000 187.000 268.000 58.262 253.044 10e-12 48.45 214.7
Local RMS Time Jitter 0.263 0.383 0.450 0.675 1.005 1.182 2.793 0.555 0.799 0.172 0.695 µs 38.24 159.1
Server Jitter 169.229.128.134 0.139 0.245 0.388 1.025 9.955 14.933 24.965 9.568 14.688 3.131 2.052 ms 2.459 13.42
Server Jitter 173.11.101.155 0.350 0.677 0.968 1.956 9.937 22.104 53.628 8.969 21.427 4.164 3.147 ms 5.158 51.2
Server Jitter 192.168.1.11 0.047 0.102 0.143 0.322 2.405 11.277 22.150 2.261 11.175 1.874 0.740 ms 4.067 33.18
Server Jitter 209.50.50.228 0.203 0.299 0.406 1.054 10.554 14.394 21.340 10.148 14.094 3.183 2.197 ms 1.915 8.566
Server Jitter 216.218.254.202 0.168 0.257 0.392 1.115 10.082 15.359 22.296 9.690 15.102 3.189 2.151 ms 2.202 10.48
Server Jitter 66.220.9.122 0.186 0.262 0.388 1.133 10.575 16.633 25.227 10.187 16.371 3.423 2.209 ms 2.39 12.27
Server Jitter SHM(0) 0.027 0.066 0.098 0.285 0.901 1.290 2.777 0.804 1.224 0.266 0.367 ms 2.866 10.15
Server Jitter SHM(1) 0.102 0.240 0.324 0.646 1.270 1.653 6.020 0.946 1.413 0.300 0.702 µs 7.832 30.16
Server Offset 169.229.128.134 1.898 2.135 2.306 2.696 3.126 3.333 4.324 0.820 1.198 0.255 2.700 ms 912.2 9049
Server Offset 173.11.101.155 -2.661 -1.937 -1.359 -0.161 0.769 1.476 4.407 2.128 3.414 0.662 -0.207 ms -6.047 19.06
Server Offset 192.168.1.11 -517.448 -268.010 -166.171 16.269 283.446 347.021 625.488 449.617 615.031 141.109 31.537 µs -2.552 5.944
Server Offset 209.50.50.228 -1.029 -0.577 -0.313 3.516 4.049 4.320 4.950 4.362 4.898 1.244 3.115 ms 5.736 11.99
Server Offset 216.218.254.202 0.149 1.910 2.160 2.629 3.073 3.310 4.078 0.913 1.401 0.298 2.621 ms 498.4 4069
Server Offset 66.220.9.122 1.344 1.831 2.066 2.489 2.923 3.181 3.529 0.857 1.350 0.268 2.485 ms 592.9 5122
Server Offset SHM(0) -134.808 -133.849 -132.538 -130.075 -128.220 -126.984 -125.098 4.318 6.865 1.345 -130.177 ms -9.357e+05 9.154e+07
Server Offset SHM(1) -5.922 -1.356 -0.930 0.033 0.815 1.184 2.806 1.745 2.540 0.532 -0.000 µs -4.309 12.07
TDOP 0.500 0.520 0.580 0.830 1.280 1.540 2.110 0.700 1.020 0.213 0.855 37.64 156.3
Temp ZONE0 49.926 50.464 51.002 52.078 53.692 53.692 54.230 2.690 3.228 0.866 52.315 °C
nSats 6.000 7.000 8.000 10.000 11.000 12.000 13.000 3.000 5.000 1.112 9.569 nSat 462.1 3691
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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