HP-UX Internet Services Administrator's Guide (August 2003)
Configuring NTP
Advanced NTP Topics
Chapter 490
• 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.