HP-UX Internet Services Administrator's Guide (May 2010)
Table 4-4 Evaluating Time Sources in Australia
remote refid st t when poll reach delay offset disp
============================================================================= .otto.bf.rmit.ed 130.155.98.1
2 u 229 1024 376 16.34 7.132 7.87 .student.ntu.edu murgon.cs.mu.OZ 2 u 47 128 377 81.34
5.166 5.25 .203.31.96.1 murgon.cs.mu.OZ 2 u 13 256 373 115.74 30.147 38.54 .203.172.21.222
tick.usno.navy. 2 u 43 1024 367 866.64 47.316 65.32 -128.184.1.4 tictoc.tip.CSIR 2 u 99
128 377 13.40 -2.976 5.66 129.127.40.255 0.0.0.0 16 u - 64 0 0.00 0.000
16000.0 *tictoc.tip.CSIR .ATOM. 1 u 17 64 377 26.92 -0.071 1.71 .dishwasher1.mpc
gilja.itd.adela 3 u 164 256 376 35.78 4.769 5.66 xclepsydra.dec.c usno.pa-x.dec.c 2 u 1468 1024
376 473.36 -53.841 12.89 murgon.cs.mu.OZ .GPS. 1 u 47d 1024 0 16.19 -398.80 16000.0
-augean.eleceng. murgon.cs.mu.OZ 2 u 12 128 377 1.83 3.270 1.21 .ns.saard.net augean.eleceng.
3 u 27 64 375 0.92 -0.013 1.19 +cuscus.cc.uq.ed tictoc.tip.CSIR 2 u 28 64 376 34.91
1.981 1.27 +staff.cs.usyd.e tictoc.tip.CSIR 2 u 3 64 375 25.21 0.158 1.97 .wasat.its.deaki
tictoc.tip.CSIR 2 u 1 128 377 15.37 -2.492 1.69 .luna.its.deakin tictoc.tip.CSIR 2 u 123
128 172 16.11 -0.350 501.11 -earth.its.deaki tictoc.tip.CSIR 2 u 28 128 377 12.19 -3.582
2.15 phobos.its.deak tictoc.tip.CSIR 2 u 169 128 56 12.42 -2.325 1000.76 .sol.ccs.deakin.
tictoc.tip.CSIR 2 u 136 512 265 13.89 -1.083 251.83 +argos.eleceng.a tictoc.tip.CSIR 2 u 23
64 377 1.82 0.197 1.21 .mercury.its.dea tictoc.tip.CSIR 2 u 123 256 377 16.91 -2.584
2.94 .orion.atnf.CSIR murgon.cs.mu.OZ 2 u 111 512 376 53.51 -0.712 5.92 +smig2a.City.Uni
tictoc.tip.CSIR 2 u 49 64 376 7.14 0.268 1.07 +svdpw.City.UniS murgon.cs.mu.OZ 2 u 26
64 376 4.90 -0.833 1.88 .news.nsw.CSIRO. murgon.cs.mu.OZ 2 u 54 1024 377 135.85 43.108
62.45 +210.8.40.225 murgon.cs.mu.OZ 2 u 2 64 377 50.83 1.811 14.45 .203.103.99.66
tictoc.tip.CSIR 2 u 342 1024 376 82.82 -14.124 36.21 xpellew.ntu.edu. tictoc.tip.CSIR 2 u 408 1024
377 404.33 -159.77 161.36 xxox.lifelike.co tick.usno.navy. 2 u 494 1024 377 504.56 -59.200
5.60
This time server in Australia has one excellent stratum-1 source (tictoc.tip.CSIR)
which it is currently synchronized to, one stratum-1 source which has not responded
in a while (reach=0), and a wide selection of stratum-2 sources (desirable candidates
marked with +). Some of the stratum-2 sources are less attractive due to high delay,
offset, and dispersion numbers. They are marked x in column one.
This time server in Australia might be a good choice for you if you are reasonably
nearby, but it is probably not a good choice for time clients in North America.
When the time server in Silicon Valley is configured to use
sirius.ctr.columbia.edu and gpo.adelaide.edu as time sources, the output
from ntpq -p looks like this (about 10 minutes after daemon startup):
Table 4-5 Output from ntpq for Configuring Silicon Valley Time Server
remote refid st t when poll reach delay offset disp
=========================================================================
*REFCLK(29,1) .GPS. 0 l 25 32 377 0.00 0.413 0.03
+bigben.cac.wash .USNO. 1 u 56 64 377 39.54 -0.466 1.68
clepsydra.dec.c usno.pa-x. 2 u 122 512 377 6.32 -0.250 0.92
-clock.isc.org .GOES. 1 u 149 512 357 5.98 -3.045 0.46
hpsdlo.sdd.hp.c wwvb.col.h 2 u 25 32 126 56.29 -8.078 8.50
+tick.ucla.edu .USNO. 1 u 13 64 177 19.29 -0.265 0.26
+usno.pa-x.dec.c .USNO. 1 u 56 64 277 6.82 0.034 0.20
gpo.adelaide.ed tictoc.tip 2 u 15 16 377 470.52 54.789 0.90
sirius.ctr.colu NAVOBS1.MI 2 u 3 16 377 83.37 -8.372 1.24
The time server in Australia has a delay of 470 milliseconds, which is very similar to
the ping round-trip times seen earlier. This leads to an offset value of 54 milliseconds,
which is significantly worse than any of the other time sources. It is interesting to note
that the offest is much less than the delay, which means that the round-trip is almost
symmetric. NTP must assume the outbound and inbound travel times are equal, and
the offset value gives an idea how unequal they might be. This is considerably better
than 470/2 which would be the offset if NTP did not make this assumption. Also
interesting is the very low dispersion value, which means that the round-trip time does
54 Configuring NTP