[ntp:questions] NTP driving me nuts!

JCA 1.41421 at gmail.com
Wed Dec 27 17:13:08 UTC 2006

   I have three Linux boxes, A, B and C, running ntpd. C gets its
synchronization from some external, stratum 2 server, whereas A and B
get their synchronization from C, as a stratum 3 server.

   This setup has been working fine for months. A couple of days ago I
noticed that A and B did not seem to be in sync any more. I restarted
ntpd in A and B, making sure that A and B were synchronized with C by
hand before. They both started fine but, surely enough, they did not
seem to be keeping up with C - the local clocks on A and B started to
diverge as though ntpd were not running at all.

   C is reachable from A and B without any problems. In turn, C stays
synchronized with the external server all right - always within 0.05
seconds. Nothing has changed in A, B and C within the last few months.
I just can't understand why, all of a sudden, A and B are no
synchronizing with C at all.

  How can one even begin to diagnose this problem? ntpd on A and B is
not dumping any information to my logs. In particular, the "time
reset" messages are absent. For all practical purposes, it is as
though it were not running at all on those two boxes - however,
synchronizing by hand with C by means of ntpdate works fine on both A
and B.

   Any ideas, anyone?

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