Installing and Administering Internet Services

316 Chapter7
Configuring the Network Time Protocol (NTP)
Troubleshooting ntp
the command:
/usr/sbin/ntpdate server
The server is the name of a trusted server, such as a peer or higher-level
(lower stratum) server. If the local xntpd is unable to form any
associations, this command will return the message “No suitable server
for synchronization found.” Check the sections below for possible causes.
Time Difference Greater than 1000 seconds When evaluating
incoming time updates, clients and peers reject timefrom servers/peers if
the time difference is 1000 seconds or greater. On a non-broadcast client
or peer, the xntpd daemon will eventually die if it cannot find a suitable
server after six consecutive polls, or five polling cycles (approximately
320 seconds if using the default polling interval).
Because of this behavior, you may have to issue the following command
to synchronize the local system time with another NTP server before
starting xntpd:
/usr/sbin/ntpdate server
For HP-UX NFS Diskless Clusters, the /sbin/init.d/xntpd script on
the diskless clients will execute xntpdate to synchronize time with the
diskless cluster server before starting xntpd.
You can also explicitly specify a trusted time server in
/etc/rc.config.d/netdaemons, and /sbin/init.d/xntpd will execute
xntpdate, querying the specified time server.
Startup Delay When xntpd first starts, it takes five poll cycles (320
seconds using the default polling interval) to form an association with a
higher-level server or peer. During this time window, xntpd will not
respond to time requests from other NTP systems, since it does not have
a suitable time source. This window exists even if xntpd is using an
external clock, which can be either an attached radio clock (Netclock/2
WWVB Synchronized Clock) or the local system clock (server
127.127. n.n ).
For external clocks, xntpd will not form a complete association until it
has sent five successful polls to itself using the local loopback address.
Problem 2: Version 1 and 2 NTP Servers Do Not Respond
NTP version 3 packets (HP-UX 10.0 NTP is version 3) are ignored by
NTP version 1 and version 2 systems. The solution is to indicate the
version 1 and 2 systems in the configuration entries on the version 3