[ntp:questions] ntp not updating the time

Marc Fromm Marc.Fromm at wwu.edu
Tue Apr 13 23:13:09 UTC 2010

I am using RedHat 5.2 and running ntp-4.2.2p1-9.el5_4.1.

The server loses 1 second per minute.
I've been checking it since I manually updated the time and after 2 hours it is 2 minutes and 1 second behind.

ntpq -p produces the following:
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================  .ACTS.           1 u  858 1024  374    4.431  62588.8 21305.0
*LOCAL(0)        .LOCL.          10 l   16   64  377    0.000    0.000   0.001

My ntp.conf file is all defaults except for the time server entry on line 13.
  1 # Permit time synchronization with our time source, but do not
  2 # permit the source to query or modify the service on this system.
  3 restrict default kod nomodify notrap nopeer noquery
  4 restrict -6 default kod nomodify notrap nopeer noquery
  6 # Permit all access over the loopback interface.  This could
  7 # be tightened as well, but to do so would effect some of
  8 # the administrative functions.
  9 restrict
 10 restrict -6 ::1
 12 # --- OUR TIMESERVERS -----
 13 server time-nw.nist.gov iburst
 15 # Hosts on local network are less restricted.
 16 #restrict mask nomodify notrap
 18 # Use public servers from the pool.ntp.org project.
 19 # Please consider joining the pool (http://www.pool.ntp.org/join.html).
 20 #server 0.rhel.pool.ntp.org
 21 #server 1.rhel.pool.ntp.org
 22 #server 2.rhel.pool.ntp.org
 24 #broadcast key 42     # broadcast server
 25 #broadcastclient            # broadcast client
 26 #broadcast key 42     # multicast server
 27 #multicastclient      # multicast client
 28 #manycastserver     # manycast server
 29 #manycastclient key 42  # manycast client
 31 # Undisciplined Local Clock. This is a fake driver intended for backup
 32 # and when no outside source of synchronized time is available.
 33 server # local clock
 34 fudge stratum 10
 36 # Drift file.  Put this in a directory which the daemon can write to.
 37 # No symbolic links allowed, either, since the daemon updates the file
 38 # by creating a temporary in the same directory and then rename()'ing
 39 # it to the file.
 40 driftfile /var/lib/ntp/drift
 42 # Key file containing the keys and key identifiers used when operating
 43 # with symmetric key cryptography.
 44 keys /etc/ntp/keys
 46 # Specify the key identifiers which are trusted.
 47 #trustedkey 4 8 42
 49 # Specify the key identifier to use with the ntpdc utility.
 50 #requestkey 8
 52 # Specify the key identifier to use with the ntpq utility.
 53 #controlkey 8

-----Original Message-----
From: questions-bounces+marc.fromm=wwu.edu at lists.ntp.org [mailto:questions-bounces+marc.fromm=wwu.edu at lists.ntp.org] On Behalf Of David Woolley
Sent: Tuesday, April 13, 2010 3:02 PM
To: questions at lists.ntp.org
Subject: Re: ntp not updating the time

Marc Fromm wrote:
> If I restart the ntpd service the time is updated to the correct time:
> /sbin/service ntpd restart

I.E. /etc/init.d/ntpd restart
which, although a deprecated procedure, will probably run ntpdate.

> If I run the command below the time is updated to the correct time:
> ntpdate -u time-nw.nist.gov
> If I don't do any of the above my time is never updated and the server becomes hours behind.
> How or when does ntpd automatically update the time?

When the measured error is between 128ms and 1,000 seconds and has 
persisted for about 15 minutes.  If it is less, ntpd tweaks the 
effective clock frequency every second, or asks the kernel to do so 
every tick, so as to slowly (order of hours) converge the clock onto the 
correct time.  If it is greater, ntpd aborts, as its idea of the time is 

Note, selective failures of ntpd relative to some options of ntpdate can 
be due to firewalling of UDP port 123.

The standard ntpq diagnostics (peers, rv 0, assoc, rv for every 
association id) and the syslog entries would be helpful, together with 
any local changes to the configuration file.  You should leave the sytem 
running for at least 30 minutes before running ntpq (less is possible, 
but 30 minutes should cover all likely settings).

As service is part of RedHat, not ntpd, and /etc/init.d/ntpd will also 
be part of RedHat, I assume you are using some version of RedHat, but 
you really should have told us which, and which version of ntpd.

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