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Set timezone (optional)

create symbolical link from /usr/share/zoneinfo/... to /etc/localtime:
ln -sf /usr/share/zoneinfo/Europe/Brussels /etc/localtime

Set UTC mode (optional)

if your hardware clock runs in UTC (Universal Coordinated Time) mode, add
UTC=true
to the /etc/sysconfig/clock file

Make sure ntpd is not running

Use service ntpd stop to stop it.

Choose the NTP server you will get your time from

it can be an internal server that has the NTP service open for clients, or an public NTP server. To be sure, use 2 servers. To check if you can access it, run ntpdate timeserver.ntp.ch

Edit the /etc/ntp.conf file

Rename the current file to ntp.bak.conf and make a small new one:
restrict default ignore
server timeserver.ntp.ch # Swiss time
server ntp.ucsd.edu # Univ of California, San Diego
restrict timeserver.ntp.ch mask 255.255.255.255 nomodify notrap noquery
restrict ntp.ucsd.edu mask 255.255.255.255 nomodify notrap noquery
server 127.127.1.0 # local clock
fudge 127.127.1.0 stratum 10 #so it only takes over if the rest fails
restrict 127.0.0.1 driftfile /etc/ntp/drift broadcastdelay 0.008 authenticate no

Set your system clock right

Run the following command a couple of times:
ntpdate -u timeserver.ntp.ch # or whatever server you want to use
You will see the initial diffence in time go away afer the 2nd or 3rd time.

Set hardware clock

/sbin/hwclock --systohc

Run the ntpd daemon

service ntpd start

Add ntpd to the services started at boot time

chkconfig ntpd on

Check the NTP results

ntpd -p
will show you what the difference is between your clock and that of the servers you added. You are looking for lines like

remote refid st t when poll reach delay offset jitter
==========================================================================
LOCAL LOCAL 10 l 30 64 377 0.000 0.000 0.004 *
192.168.246.107 192.168.246.88 3 u 41 128 177 0.313 5.598 0.345
and not lines like

remote refid st t when poll reach delay offset jitter
==========================================================================
192.168.246.126 LOCAL 11 u 37 128 375 0.204 6082.02 6069.84
Jitter is too high!

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