HP-UX Internet Services Administrator's Guide (May 2010)

□ - indicates a host discarded by the clustering algorithm.
□ blank indicates a host is discarded due to high stratum and/or failed sanity
checks.
• The refid (reference identification) column indicates the current source of
synchronization for the remote host. .WWVB. indicates that the host uses a radio
clock that receives time signals from the U.S. government radio station WWVB.
• The st (stratum) column indicates the stratum level of the remote host.
• The t(types) column denotes the available types, which include
— l=local (such as a GPS clock)
— u=unicast (this is the common type)
— m = multicast
— b= broadcast
— - = netaddr (usually 0)
• The when column indicates the number of seconds since the remote host response
was received.
• The poll (poll period) column indicates the polling interval to the remote host,
as determined by xntpd. You can define the minimum polling interval with the
minpoll option in the peer, server, or broadcast definitions in the
/etc/ntp.conf file. Some popular values for network connections include 512
and 1024 seconds (approximately 8 mins. and 17 mins.). Systems with external
clocks, like GPS, must poll every 64 seconds or less.
• The reach (reachability) column indicates how successful attempts to reach the
server are. This is an 8-bit shift register with the most recent probe in the 2^0
position. The value 001 indicates the most recent probe was answered, while 357
indicates one probe was not answered. The value 377 indicates that all the recent
probes have been answered.
• The delay (round trip time) column indicates the time (in milliseconds) taken by
the reply packet to return in response, to a query sent by the server.
• The offset (time difference) column indicates the time difference (in milliseconds)
between the server’s clock and the client’s clock. When this number exceeds 128,
and the message synchronization lost appears in the log file.
• The disp (dispersion) column indicates the difference in the offset measurement
between two samples. This is an error-bound estimate. The dispersion is a primary
measure of the network service quality.
Troubleshooting NTP
This section outlines techniques that can help you diagnose and correct common
problems with the NTP.
70 Configuring NTP