HP-UX Internet Services Administrator's Guide (August 2003)
Configuring NTP
Getting Started with NTP
Chapter 4 65
Determining Synchronization Sources
You can query the time server using the following command to check the
synchronization sources:
/usr/bin/ntpq -p ntp-cup.external.hp.com
Table 8-2 displays the synchronized time servers.
This time server is synchronized (asterisk in column one) to
REFCLK(29,1), which is a Trimble Palisade GPS receiver. The offset
from GPS is 0.004 milliseconds and the dispersion is 0.02 milliseconds.
This time server also has several good stratum-1 and stratum-2 servers
which it can fall back if the GPS receiver stops functioning.
The entry for the time server hpsdlo.sdd.hp.com has a delay, offset,
and dispersion measures less than any of the other sources. The time
server hpsdlo is good, but the network in between has some problems,
depicted by the large dispersion figures. If the dispersion numbers are
high, contact the network service provider.
The time server ntp-cup.external.hp.com is the appropriate time
server because it is only 5 milliseconds from the NTP client and it the
right choice for a public time server. The ping command round-trip time
determines whether this time server is the right choice for a public time
server.
Example 2: Evaluating Time Servers in Eastern United States
For a time server located on the east coast of Northern America,
following are the details:
ntp.ctr.columbia.edu (128.59.64.60)
Location: Columbia University Center for Telecommunications Re
search; NYC
Table 4-2 Locating Synchronized Time Servers
remote refid st t when poll reach delay offset disp
============================================================================
*REFCLK(29,1) .GPS. 0 l 35 32 376 0.00 -0.004 0.02
-bigben.cac.wash .USNO. 1 u 47 128 377 40.16 -1.244 1.37
clepsydra.dec.c usno.pa 2 u 561 1024 377 16.74 -4.563 4.21
-clock.isc.org .GOES. 1 u 418 1024 377 6.87 -3.766 3.57
hpsdlo.sdd.hp.c wwvb.col. 2 u 34 16 204 48.17 -8.584 926.35
+tick.ucla.edu .USNO. 1 u 111 128 377 20.03 -0.178 0.43
+usno.pa-x.dec.c .USNO. 1 u 42 128 377 6.96 -0.408 0.38