HP-UX Internet Services Administrator's Guide (February 2007)

Following is the stratum-2 listing of the an HP machine which was provided in the
Silicon Valley for public use in North America.
ntp-cup.external.hp.com (192.6.38.127) Location: Cupertino CA (SF Bay area) 37:20N/122:00W
Synchronization: NTPv3 primary (GPS), HP-UX Service Area: West Coast USA Access Policy: open access
Contact: [e-mail] Note: no need to notify for access, go right ahead!
If you are located in Silicon Valley, you can ping this time server and notice that the
time server is 5 milliseconds.
/usr/sbin/ping ntp-cup.external.hp.com 64 5 PING ntp-cup.external.hp.com: 64 byte packets
64 bytes from 192.6.38.127: icmp_seq=0. time=5. ms 64 bytes from 192.6.38.127: icmp_seq=1. time=4. ms
64 bytes from 192.6.38.127: icmp_seq=2. time=4. ms 64 bytes from 192.6.38.127: icmp_seq=3. time=5. ms
64 bytes from 192.6.38.127: icmp_seq=4. time=5. ms ----ntp-cup.external.hp.com PING Statistics---
5 packets transmitted, 5 packets received, 0% packet loss round-trip (ms) min/avg/max = 4/4/5
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 4-2 displays the synchronized time servers.
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
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:
Getting Started with NTP 53