Sync Time with pool.ntp.org

 

RHEL

* Open NTP port 123:
vi /etc/sysconfig/iptables

:RH-Firewall-1-INPUT - [0:0]
# Open NTP port 123
-I INPUT -p udp -m udp -m multiport --dports 123 -m state --state NEW -j ACCEPT
-A INPUT -j RH-Firewall-1-INPUT

* Restart iptables

service iptables restart

* Configure NTP server
vi /etc/ntp.conf

server pool.ntp.org

* Restart ntpd

service ntpd restart

* Check NTP status with ntpstat

ntpstat
synchronised to NTP server (198.58.100.237) at stratum 3
   time correct to within 97 ms
   polling server every 64 s

* Check NTP host with ntpq -p

ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*tux.brhelwig.co 216.218.254.202  2 u   11  128  377   46.408    0.703   0.647
 LOCAL(0)        .LOCL.          10 l   13   64  377    0.000    0.000   0.001

Windows

* See Windows Time Service Tools and Settings
* NTP time service in Windows 2003

ESXi 5.1

* Login vSphere
* Click host > Configuration > Time Configuration > Properties
* Select NTP Client Enabled

* Click Options > General
– Select Start automatically…

* Click NTP Settings
* Click Add… to add pool.ntp.org
* Check Restart NTP service to apply changes and click OK

References

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