2001-08-29 14:35:15 +00:00
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
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<meta name="generator" content="HTML Tidy, see www.w3.org">
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<title>ntptrace - trace a chain of NTP servers back to the primary
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source</title>
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</head>
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<body>
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<h3><tt>ntptrace</tt> - trace a chain of NTP servers back to the
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primary source</h3>
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<img align="left" src="pic/alice13.gif" alt="gif"><a href=
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"http://www.eecis.udel.edu/~mills/pictures.htm">from <i>Alice's
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Adventures in Wonderland</i>, Lewis Carroll</a>
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<p>The rabbit knows the way back.<br clear="left">
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</p>
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<hr>
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<h4>Synopsis</h4>
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<tt>ntptrace [ -vdn ] [ -r <i>retries</i> ] [ -t <i>timeout</i> ] [
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<i>server</i> ]</tt>
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<h4>Description</h4>
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<p><tt>ntptrace</tt> determines where a given Network Time Protocol
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(NTP) server gets its time from, and follows the chain of NTP
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servers back to their master time source. If given no arguments, it
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starts with <tt>localhost</tt>. Here is an example of the output
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from <tt>ntptrace</tt>:</p>
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<pre>
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% ntptrace
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1999-12-09 13:01:21 +00:00
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localhost: stratum 4, offset 0.0019529, synch distance 0.144135
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server2ozo.com: stratum 2, offset 0.0124263, synch distance 0.115784
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usndh.edu: stratum 1, offset 0.0019298, synch distance 0.011993, refid
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2001-08-29 14:35:15 +00:00
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'WWVB'
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</pre>
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On each line, the fields are (left to right): the host name, the
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host stratum, the time offset between that host and the local host
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(as measured by <tt>ntptrace</tt>; this is why it is not always
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zero for "<tt>localhost</tt>"), the host synchronization distance,
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and (only for stratum-1 servers) the reference clock ID. All times
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are given in seconds. Note that the stratum is the server hop count
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to the primary source, while the synchronization distance is the
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estimated error relative to the primary source. These terms are
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precisely defined in RFC-1305.
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<h4>Options</h4>
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<dl>
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<dt><tt>-d</tt></dt>
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<dd>Turns on some debugging output.</dd>
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<dt><tt>-n</tt></dt>
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<dd>Turns off the printing of host names; instead, host IP
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addresses are given. This may be useful if a nameserver is
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down.</dd>
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<dt><tt>-r <i>retries</i></tt></dt>
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<dd>Sets the number of retransmission attempts for each host
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(default = 5).</dd>
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<dt><tt>-t <i>timeout</i></tt></dt>
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<dd>Sets the retransmission timeout (in seconds) (default =
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2).</dd>
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<dt><tt>-v</tt></dt>
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<dd>Prints verbose information about the NTP servers.</dd>
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</dl>
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<h4>Bugs</h4>
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This program makes no attempt to improve accuracy by doing multiple
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samples.
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<hr>
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<a href="index.htm"><img align="left" src="pic/home.gif" alt=
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"gif"></a>
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<address><a href="mailto:mills@udel.edu">David L. Mills
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<mills@udel.edu></a></address>
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</body>
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</html>
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