[CentOS] Time delaying (or time lagging)

John R Pierce pierce at hogranch.com
Sat Sep 6 20:56:39 UTC 2008

happymaster23 wrote:
> Hello everyone,
> I have problem with time delaying on my CentOS powered server. I have 
> tried to set time in BIOS and in OS (with saving time to BIOS), but 
> time still delaying, so after month is about five minutes delayed. In 
> past I was using this box with Windows and there wasn´t this time 
> problem, but I cant warrant, that there are no hardware issues. So I 
> was decided, that easiest way to fix this problem will be setting up 
> the NTP. I have found many howtos, but I don´t believe them. So my 
> question is: How to clearly set NTP in CentOS 5?

    # yum install ntp

then, edit /etc/ntp.conf, and at a minimum specify some ntp servers and 
restrict access to localhost...

    restrict -6 ::1

    # Use public servers from the pool.ntp.org project.
    # Please consider joining the pool (http://www.pool.ntp.org/join.html).
    server ntp1.sf-bay.org
    server ntp2.sf-bay.org
    server reloj.kjsl.com
    server ntp1.mainecoon.com
    server ntp2.mainecoon.com
    server time.berkeley.netdot.net

(note, those are the LOCAL TO ME ntp servers that *I* am using, you 
should undoubtedly use others as appropriate, or use the pool servers... 
see http://ntp.isc.org/bin/view/Servers/WebHome for guidelines)...


    # chkconfig ntpd on
    # service ntpd start

and wait about 20 mins for it to sync up, and verify functionality with 

    # ntptrace
    localhost.localdomain: stratum 3, offset 0.004351, synch distance 
    zorro.sf-bay.org: stratum 2, offset 0.000543, synch distance 0.044773
    clock.via.net: stratum 1, offset 0.000027, synch distance 0.000446, 
refid 'GPS'

if your systems clock is particularlly funky, it may be a good idea to 
edit, /etc/sysconfig/ntpd  and set SYNC_HWCLOCK=yes rather than no.
(this tells it to set your HW CMOS clock when it sets the system clock 
during the initial synchronization)

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