On Tue, May 20, 2008 at 3:46 PM, Alfred von Campe <alfred at von-campe.com> wrote: > I have 30 identical Lenovo desktop systems running CentOS 5.1. On one of > those systems the clock is running slow (5+ minutes from yesterday to this > morning and another minute since this morning) despite the fact that NTP is > running on all of them and they all have the exact same /etc/ntp.conf file > (I compared the MD5 sums of that file on all the systems). Here is the > output of "grep ntp /var/log messages" on the system with the problem since > I restarted the NTP daemon earlier today: Hi Alfred, What is the output of "ntpq -np" ? You should have a line with a star (*), otherwise it is not synchronizing. Start running NTP again, wait for half an hour and issue that command to see what your output is. It could be a problem related to filtering UDP traffic, either with iptables on the machine itself, or some other router in the network your machine is in. HTH, Filipe