NTPsec

A-ntpsec-3-hour-stats

Report generated: Wed Aug 17 20:04:26 2022 UTC
Start Time: Wed Aug 17 17:04:25 2022 UTC
End Time: Wed Aug 17 20:04:25 2022 UTC
Report published: Wed Aug 17 13:04:31 2022 PDT
Report Period: 0.1 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 -16.468 -2.789 -1.933 0.011 1.905 2.508 3.949 3.838 5.297 1.222 -0.000 µs -4.734 19.6
Local Clock Frequency Offset -57.953 -43.869 -40.482 -28.992 -19.455 -16.266 -10.956 21.027 27.603 6.551 -29.465 ppb -182.9 1102

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 0.739 0.890 1.040 1.490 2.080 2.677 8.612 1.040 1.787 0.412 1.525 µs 32.78 216.7

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 1.138 1.397 1.605 2.224 3.189 4.195 11.576 1.584 2.798 0.599 2.306 ppb 36.05 214.2

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 -16.468 -2.789 -1.933 0.011 1.905 2.508 3.949 3.838 5.297 1.222 -0.000 µs -4.734 19.6

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 -57.953 -43.869 -40.482 -28.992 -19.455 -16.266 -10.956 21.027 27.603 6.551 -29.465 ppb -182.9 1102
Temp ZONE0 53.692 53.692 53.692 54.230 54.768 54.768 54.768 1.076 1.076 0.409 54.085 °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 8.000 9.000 9.000 10.000 12.000 12.000 12.000 3.000 3.000 0.858 10.270 nSat 1353 1.521e+04
TDOP 0.590 0.590 0.610 0.760 1.130 1.300 1.310 0.520 0.710 0.166 0.827 75.79 358.5

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 1.106 1.106 1.628 2.295 2.681 2.721 2.721 1.052 1.615 0.320 2.245 ms 234.8 1506

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 -2.033 -2.033 -1.333 -0.207 0.592 0.806 0.806 1.925 2.840 0.548 -0.271 ms -8.663 27.65

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 -570.381 -357.717 -155.746 158.759 444.567 628.987 867.179 600.313 986.704 185.166 143.235 µs -0.7695 5.253

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 1.585 1.585 1.781 2.328 2.744 2.824 2.824 0.963 1.239 0.299 2.346 ms 339.9 2458

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 1.888 1.888 1.978 2.493 2.736 2.810 2.810 0.758 0.923 0.223 2.447 ms 1021 1.046e+04

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 45.33.37.82

peer offset 45.33.37.82 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 45.33.37.82 0.941 0.941 1.423 2.420 3.062 3.754 3.754 1.639 2.813 0.446 2.385 ms 95.06 472

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) -55.684 -54.279 -53.577 -50.378 -46.263 -45.244 -44.299 7.313 9.035 2.300 -50.172 ms -1.194e+04 2.739e+05

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) -16.469 -2.790 -1.934 0.012 1.906 2.509 3.950 3.840 5.299 1.222 -0.000 µs -4.733 19.58

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 0.388 0.388 0.493 1.511 4.543 15.710 15.710 4.051 15.322 2.589 2.047 ms 3.586 18.97

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 1.160 1.160 1.192 2.142 5.027 5.635 5.635 3.835 4.475 1.260 2.505 ms 4.89 13.37

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 0.187 0.223 0.332 0.786 5.753 12.073 14.140 5.420 11.850 1.887 1.505 ms 2.63 14.37

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 0.426 0.426 0.458 1.078 6.605 20.903 20.903 6.148 20.476 3.601 2.125 ms 3.181 16.9

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 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 0.636 0.636 0.647 1.382 2.748 3.104 3.104 2.101 2.468 0.739 1.720 ms 6.585 16.69

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 45.33.37.82

peer jitter 45.33.37.82 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 45.33.37.82 0.448 0.448 0.676 1.550 6.697 8.026 8.026 6.021 7.578 2.191 2.523 ms 1.701 3.838

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) 0.077 0.192 0.306 0.828 2.187 2.881 3.432 1.880 2.689 0.579 0.982 ms 3.692 11.25

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) 0.326 0.587 0.797 1.474 2.864 3.674 16.162 2.067 3.087 0.725 1.617 µs 8.925 70.3

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 -57.953 -43.869 -40.482 -28.992 -19.455 -16.266 -10.956 21.027 27.603 6.551 -29.465 ppb -182.9 1102
Local Clock Time Offset -16.468 -2.789 -1.933 0.011 1.905 2.508 3.949 3.838 5.297 1.222 -0.000 µs -4.734 19.6
Local RMS Frequency Jitter 1.138 1.397 1.605 2.224 3.189 4.195 11.576 1.584 2.798 0.599 2.306 ppb 36.05 214.2
Local RMS Time Jitter 0.739 0.890 1.040 1.490 2.080 2.677 8.612 1.040 1.787 0.412 1.525 µs 32.78 216.7
Server Jitter 169.229.128.134 0.388 0.388 0.493 1.511 4.543 15.710 15.710 4.051 15.322 2.589 2.047 ms 3.586 18.97
Server Jitter 173.11.101.155 1.160 1.160 1.192 2.142 5.027 5.635 5.635 3.835 4.475 1.260 2.505 ms 4.89 13.37
Server Jitter 192.168.1.11 0.187 0.223 0.332 0.786 5.753 12.073 14.140 5.420 11.850 1.887 1.505 ms 2.63 14.37
Server Jitter 216.218.192.202 0.426 0.426 0.458 1.078 6.605 20.903 20.903 6.148 20.476 3.601 2.125 ms 3.181 16.9
Server Jitter 216.218.254.202 0.636 0.636 0.647 1.382 2.748 3.104 3.104 2.101 2.468 0.739 1.720 ms 6.585 16.69
Server Jitter 45.33.37.82 0.448 0.448 0.676 1.550 6.697 8.026 8.026 6.021 7.578 2.191 2.523 ms 1.701 3.838
Server Jitter SHM(0) 0.077 0.192 0.306 0.828 2.187 2.881 3.432 1.880 2.689 0.579 0.982 ms 3.692 11.25
Server Jitter SHM(1) 0.326 0.587 0.797 1.474 2.864 3.674 16.162 2.067 3.087 0.725 1.617 µs 8.925 70.3
Server Offset 169.229.128.134 1.106 1.106 1.628 2.295 2.681 2.721 2.721 1.052 1.615 0.320 2.245 ms 234.8 1506
Server Offset 173.11.101.155 -2.033 -2.033 -1.333 -0.207 0.592 0.806 0.806 1.925 2.840 0.548 -0.271 ms -8.663 27.65
Server Offset 192.168.1.11 -570.381 -357.717 -155.746 158.759 444.567 628.987 867.179 600.313 986.704 185.166 143.235 µs -0.7695 5.253
Server Offset 216.218.192.202 1.585 1.585 1.781 2.328 2.744 2.824 2.824 0.963 1.239 0.299 2.346 ms 339.9 2458
Server Offset 216.218.254.202 1.888 1.888 1.978 2.493 2.736 2.810 2.810 0.758 0.923 0.223 2.447 ms 1021 1.046e+04
Server Offset 45.33.37.82 0.941 0.941 1.423 2.420 3.062 3.754 3.754 1.639 2.813 0.446 2.385 ms 95.06 472
Server Offset SHM(0) -55.684 -54.279 -53.577 -50.378 -46.263 -45.244 -44.299 7.313 9.035 2.300 -50.172 ms -1.194e+04 2.739e+05
Server Offset SHM(1) -16.469 -2.790 -1.934 0.012 1.906 2.509 3.950 3.840 5.299 1.222 -0.000 µs -4.733 19.58
TDOP 0.590 0.590 0.610 0.760 1.130 1.300 1.310 0.520 0.710 0.166 0.827 75.79 358.5
Temp ZONE0 53.692 53.692 53.692 54.230 54.768 54.768 54.768 1.076 1.076 0.409 54.085 °C
nSats 8.000 9.000 9.000 10.000 12.000 12.000 12.000 3.000 3.000 0.858 10.270 nSat 1353 1.521e+04
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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