NTPsec

A-ntpsec-72-hour-stats

Report generated: Sun Mar 3 04:07:53 2024 UTC
Start Time: Thu Feb 29 04:07:51 2024 UTC
End Time: Sun Mar 3 04:07:51 2024 UTC
Report published: Sat Mar 02 08:08:06 PM 2024 PST
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 -2.056 -1.323 -0.958 0.017 0.858 1.261 2.591 1.816 2.584 0.550 -0.006 µs -4.177 10.71
Local Clock Frequency Offset -578.110 -573.273 -541.397 -339.523 -262.283 -224.274 -221.558 279.114 348.999 87.196 -366.979 ppb -157.6 915.6

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 0.272 0.408 0.476 0.693 0.997 1.162 1.548 0.521 0.754 0.161 0.710 µs 50.69 218.2

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 108.000 157.000 181.000 259.000 362.000 414.000 567.000 181.000 257.000 54.910 263.368 10e-12 66.64 305.8

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 -2.056 -1.323 -0.958 0.017 0.858 1.261 2.591 1.816 2.584 0.550 -0.006 µs -4.177 10.71

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 -578.110 -573.273 -541.397 -339.523 -262.283 -224.274 -221.558 279.114 348.999 87.196 -366.979 ppb -157.6 915.6
Temp ZONE0 44.008 44.546 45.084 46.698 47.774 48.312 48.312 2.690 3.766 0.913 46.500 °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 7.000 8.000 8.000 10.000 12.000 12.000 12.000 4.000 4.000 1.069 9.751 nSat 561.1 4766
TDOP 0.500 0.510 0.580 0.820 1.200 1.300 1.700 0.620 0.790 0.192 0.844 50.01 213.2

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 162.159.200.1

peer offset 162.159.200.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 162.159.200.1 1.014 3.536 4.024 4.609 195.785 310.018 441.556 191.761 306.483 62.112 20.756 ms 1.602 9.863

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 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 -0.180 0.968 1.367 1.899 206.778 300.023 493.512 205.411 299.055 64.681 18.509 ms 1.604 11.89

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 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 -12.470 -4.552 -2.334 0.038 201.306 297.535 498.796 203.640 302.087 65.211 17.245 ms 1.31 10.52

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 216.218.192.202

peer offset 216.218.192.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 216.218.192.202 -0.774 1.560 2.029 2.553 203.318 311.096 494.682 201.289 309.536 61.906 18.788 ms 1.449 9.98

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 0.578 1.747 2.058 2.580 207.096 328.848 493.213 205.038 327.101 67.028 20.520 ms 1.453 9.908

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 52.10.183.132

peer offset 52.10.183.132 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 52.10.183.132 2.253 2.651 3.221 4.892 192.956 320.199 463.434 189.735 317.548 62.080 20.624 ms 1.686 10.61

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) -102.974 -101.661 -99.929 -96.976 -94.977 -94.154 -93.156 4.952 7.507 1.498 -97.174 ms -2.861e+05 1.886e+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) -2.057 -1.324 -0.959 0.018 0.859 1.262 2.592 1.818 2.586 0.551 -0.006 µs -4.176 10.7

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 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 162.159.200.1

peer jitter 162.159.200.1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 162.159.200.1 0.295 0.401 0.662 1.790 168.066 269.111 476.014 167.404 268.710 56.492 17.808 ms 1.67 12.7

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 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 0.257 0.398 0.647 1.649 149.373 317.848 448.298 148.726 317.451 57.522 17.609 ms 1.812 13.83

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 0.000 0.862 1.360 3.658 152.095 258.502 473.820 150.735 257.640 53.390 18.200 ms 1.952 14.58

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 216.218.192.202

peer jitter 216.218.192.202 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 216.218.192.202 0.290 0.432 0.675 1.735 147.296 247.182 463.980 146.621 246.751 52.654 16.353 ms 1.8 13.94

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 0.190 0.355 0.664 1.735 168.118 266.090 471.381 167.454 265.735 58.440 19.178 ms 1.483 11.23

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 52.10.183.132

peer jitter 52.10.183.132 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 52.10.183.132 0.300 0.430 0.646 1.879 159.018 253.807 466.569 158.372 253.377 54.004 16.770 ms 1.803 13.81

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 0.070 0.101 0.311 0.991 1.397 2.442 0.890 1.326 0.295 0.401 ms 2.68 9.006

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) 0.105 0.256 0.347 0.666 1.279 1.634 2.663 0.932 1.378 0.291 0.721 µs 8.768 29.2

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.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -578.110 -573.273 -541.397 -339.523 -262.283 -224.274 -221.558 279.114 348.999 87.196 -366.979 ppb -157.6 915.6
Local Clock Time Offset -2.056 -1.323 -0.958 0.017 0.858 1.261 2.591 1.816 2.584 0.550 -0.006 µs -4.177 10.71
Local RMS Frequency Jitter 108.000 157.000 181.000 259.000 362.000 414.000 567.000 181.000 257.000 54.910 263.368 10e-12 66.64 305.8
Local RMS Time Jitter 0.272 0.408 0.476 0.693 0.997 1.162 1.548 0.521 0.754 0.161 0.710 µs 50.69 218.2
Server Jitter 162.159.200.1 0.295 0.401 0.662 1.790 168.066 269.111 476.014 167.404 268.710 56.492 17.808 ms 1.67 12.7
Server Jitter 169.229.128.134 0.257 0.398 0.647 1.649 149.373 317.848 448.298 148.726 317.451 57.522 17.609 ms 1.812 13.83
Server Jitter 173.11.101.155 0.000 0.862 1.360 3.658 152.095 258.502 473.820 150.735 257.640 53.390 18.200 ms 1.952 14.58
Server Jitter 216.218.192.202 0.290 0.432 0.675 1.735 147.296 247.182 463.980 146.621 246.751 52.654 16.353 ms 1.8 13.94
Server Jitter 216.218.254.202 0.190 0.355 0.664 1.735 168.118 266.090 471.381 167.454 265.735 58.440 19.178 ms 1.483 11.23
Server Jitter 52.10.183.132 0.300 0.430 0.646 1.879 159.018 253.807 466.569 158.372 253.377 54.004 16.770 ms 1.803 13.81
Server Jitter SHM(0) 0.027 0.070 0.101 0.311 0.991 1.397 2.442 0.890 1.326 0.295 0.401 ms 2.68 9.006
Server Jitter SHM(1) 0.105 0.256 0.347 0.666 1.279 1.634 2.663 0.932 1.378 0.291 0.721 µs 8.768 29.2
Server Offset 162.159.200.1 1.014 3.536 4.024 4.609 195.785 310.018 441.556 191.761 306.483 62.112 20.756 ms 1.602 9.863
Server Offset 169.229.128.134 -0.180 0.968 1.367 1.899 206.778 300.023 493.512 205.411 299.055 64.681 18.509 ms 1.604 11.89
Server Offset 173.11.101.155 -12.470 -4.552 -2.334 0.038 201.306 297.535 498.796 203.640 302.087 65.211 17.245 ms 1.31 10.52
Server Offset 216.218.192.202 -0.774 1.560 2.029 2.553 203.318 311.096 494.682 201.289 309.536 61.906 18.788 ms 1.449 9.98
Server Offset 216.218.254.202 0.578 1.747 2.058 2.580 207.096 328.848 493.213 205.038 327.101 67.028 20.520 ms 1.453 9.908
Server Offset 52.10.183.132 2.253 2.651 3.221 4.892 192.956 320.199 463.434 189.735 317.548 62.080 20.624 ms 1.686 10.61
Server Offset SHM(0) -102.974 -101.661 -99.929 -96.976 -94.977 -94.154 -93.156 4.952 7.507 1.498 -97.174 ms -2.861e+05 1.886e+07
Server Offset SHM(1) -2.057 -1.324 -0.959 0.018 0.859 1.262 2.592 1.818 2.586 0.551 -0.006 µs -4.176 10.7
TDOP 0.500 0.510 0.580 0.820 1.200 1.300 1.700 0.620 0.790 0.192 0.844 50.01 213.2
Temp ZONE0 44.008 44.546 45.084 46.698 47.774 48.312 48.312 2.690 3.766 0.913 46.500 °C
nSats 7.000 8.000 8.000 10.000 12.000 12.000 12.000 4.000 4.000 1.069 9.751 nSat 561.1 4766
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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