Install and configure NTP server on Linux

It's an example to install and Configure NTP server for system clock.
[root@ns ~]# yum -y install ntp
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: ftp.jaist.ac.jp
* base: ftp.jaist.ac.jp
* extras: ftp.jaist.ac.jp
* updates: ftp.jaist.ac.jp
Setting up Install Process
Resolving Dependencies
--> Running transaction check
--> Package ntp.x86_64 0:4.2.2p1-9.el5.centos.2 set to be updated
--> Finished Dependency Resolution



Dependencies Resolved

===================================================================
Package Arch Version Repository Size
===================================================================
Installing:
  ntp x86_64 4.2.2p1-9.el5.centos.2 base 1.3 M

Transaction Summary
===================================================================
Install 1 Package(s)
Update 0 Package(s)
Remove 0 Package(s)

Total download size: 1.3 M
Downloading Packages:
(1/1): ntp-4.2.2p1-9.el5.100% |====================| 1.3 MB 00:00
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing:   ntp#################################### [1/1]

Installed: ntp.x86_64 0:4.2.2p1-9.el5.centos.2
Complete!
[root@ns ~]# mv /etc/ntp.conf /etc/ntp.conf.bk
[root@ns ~]# vi /etc/ntp.conf

# Set servers for synchronizing
server ntp1.jst.mfeed.ad.jp
server ntp2.jst.mfeed.ad.jp
server ntp3.jst.mfeed.ad.jp

[root@ns ~]# /etc/rc.d/init.d/ntpd start
Starting ntpd:[ OK ]
[root@ns ~]# chkconfig ntpd on
[root@ns ~]# ntpq -p
remote refid st t when poll reach delay offset jitter
==========================================================
ntp1.jst.mfeed.210.173.160.862 u2641 21.227-475.550.001
ntp2.jst.mfeed.210.173.160.862u 164121.400 -475.530.001
ntp3.jst.mfeed.210.173.160.862u -64122.087 -476.080.001