[CentOS] Strange NTP problem

Tue May 20 19:46:04 UTC 2008
Alfred von Campe <alfred at von-campe.com>

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:

May 20 11:35:38 hepdsw03 ntpd[31791]: ntpd 4.2.2p1 at 1.1570-o Sat Nov  
10 12:33:50 UTC 2007 (1)
May 20 11:35:38 hepdsw03 ntpd[31792]: precision = 1.000 usec
May 20 11:35:38 hepdsw03 ntpd[31792]: Listening on interface  
wildcard, 0.0.0.0#123 Disabled
May 20 11:35:38 hepdsw03 ntpd[31792]: Listening on interface  
wildcard, ::#123 Disabled
May 20 11:35:38 hepdsw03 ntpd[31792]: Listening on interface lo, :: 
1#123 Enabled
May 20 11:35:38 hepdsw03 ntpd[31792]: Listening on interface eth0,  
fe80::210:c6ff:feab:dd92#123 Enabled
May 20 11:35:38 hepdsw03 ntpd[31792]: Listening on interface lo,  
127.0.0.1#123 Enabled
May 20 11:35:38 hepdsw03 ntpd[31792]: Listening on interface eth0,  
10.66.42.109#123 Enabled
May 20 11:35:38 hepdsw03 ntpd[31792]: kernel time sync status 0040
May 20 11:35:38 hepdsw03 ntpd[31792]: frequency initialized 0.000 PPM  
from /var/lib/ntp/drift
May 20 11:38:55 hepdsw03 ntpd[31792]: synchronized to LOCAL(0),  
stratum 10
May 20 11:38:55 hepdsw03 ntpd[31792]: kernel time sync disabled 0001
May 20 11:39:59 hepdsw03 ntpd[31792]: synchronized to 10.101.32.104,  
stratum 3
May 20 11:40:58 hepdsw03 ntpd[31792]: synchronized to LOCAL(0),  
stratum 10
May 20 11:42:09 hepdsw03 ntpd[31792]: synchronized to 10.101.32.104,  
stratum 3
May 20 11:47:26 hepdsw03 ntpd[31792]: synchronized to LOCAL(0),  
stratum 10
May 20 11:49:31 hepdsw03 ntpd[31792]: synchronized to 10.101.32.104,  
stratum 3
May 20 11:52:48 hepdsw03 ntpd[31792]: synchronized to LOCAL(0),  
stratum 10
May 20 11:54:54 hepdsw03 ntpd[31792]: synchronized to 10.101.32.104,  
stratum 3
May 20 12:01:26 hepdsw03 ntpd[31792]: synchronized to LOCAL(0),  
stratum 10

Any idea what could be causing this?  For now I have disabled the NTP  
daemon and am running ntpdate once an hour.  What complicates the  
matter is that we are using Kerberos for authentication, and after a  
day or so the user can not log into his system anymore because of the  
time skew.

Alfred