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5 | <title>ntptrace - trace a chain of NTP servers back to the primary |
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6 | source</title> |
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7 | </head> |
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8 | <body> |
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9 | <h3><tt>ntptrace</tt> - trace a chain of NTP servers back to the |
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10 | primary source</h3> |
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11 | |
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12 | <img align="left" src="pic/alice13.gif" alt="gif"><a href= |
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13 | "http://www.eecis.udel.edu/~mills/pictures.htm">from <i>Alice's |
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14 | Adventures in Wonderland</i>, Lewis Carroll</a> |
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15 | |
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16 | <p>The rabbit knows the way back.<br clear="left"> |
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17 | </p> |
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18 | |
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19 | <hr> |
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20 | <h4>Synopsis</h4> |
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21 | |
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22 | <tt>ntptrace [ -vdn ] [ -r <i>retries</i> ] [ -t <i>timeout</i> ] [ |
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23 | <i>server</i> ]</tt> |
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24 | |
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25 | <h4>Description</h4> |
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26 | |
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27 | <p><tt>ntptrace</tt> determines where a given Network Time Protocol |
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28 | (NTP) server gets its time from, and follows the chain of NTP |
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29 | servers back to their master time source. If given no arguments, it |
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30 | starts with <tt>localhost</tt>. Here is an example of the output |
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31 | from <tt>ntptrace</tt>:</p> |
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32 | |
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33 | <pre> |
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34 | % ntptrace |
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35 | localhost: stratum 4, offset 0.0019529, synch distance 0.144135 |
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36 | server2ozo.com: stratum 2, offset 0.0124263, synch distance 0.115784 |
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37 | usndh.edu: stratum 1, offset 0.0019298, synch distance 0.011993, refid |
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38 | 'WWVB' |
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39 | </pre> |
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40 | |
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41 | On each line, the fields are (left to right): the host name, the |
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42 | host stratum, the time offset between that host and the local host |
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43 | (as measured by <tt>ntptrace</tt>; this is why it is not always |
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44 | zero for "<tt>localhost</tt>"), the host synchronization distance, |
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45 | and (only for stratum-1 servers) the reference clock ID. All times |
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46 | are given in seconds. Note that the stratum is the server hop count |
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47 | to the primary source, while the synchronization distance is the |
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48 | estimated error relative to the primary source. These terms are |
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49 | precisely defined in RFC-1305. |
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50 | |
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51 | <h4>Options</h4> |
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52 | |
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53 | <dl> |
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54 | <dt><tt>-d</tt></dt> |
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55 | |
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56 | <dd>Turns on some debugging output.</dd> |
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57 | |
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58 | <dt><tt>-n</tt></dt> |
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59 | |
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60 | <dd>Turns off the printing of host names; instead, host IP |
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61 | addresses are given. This may be useful if a nameserver is |
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62 | down.</dd> |
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63 | |
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64 | <dt><tt>-r <i>retries</i></tt></dt> |
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65 | |
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66 | <dd>Sets the number of retransmission attempts for each host |
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67 | (default = 5).</dd> |
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68 | |
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69 | <dt><tt>-t <i>timeout</i></tt></dt> |
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70 | |
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71 | <dd>Sets the retransmission timeout (in seconds) (default = |
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72 | 2).</dd> |
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73 | |
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74 | <dt><tt>-v</tt></dt> |
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75 | |
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76 | <dd>Prints verbose information about the NTP servers.</dd> |
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77 | </dl> |
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78 | |
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79 | <h4>Bugs</h4> |
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80 | |
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81 | This program makes no attempt to improve accuracy by doing multiple |
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82 | samples. |
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83 | |
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84 | <hr> |
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85 | <a href="index.htm"><img align="left" src="pic/home.gif" alt= |
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86 | "gif"></a> |
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87 | <address><a href="mailto:mills@udel.edu">David L. Mills |
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88 | <mills@udel.edu></a></address> |
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89 | </body> |
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90 | </html> |
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91 | |
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