Configure NTP

Eucalyptus requires that each machine have the Network Time Protocol (NTP) daemon started and configured to run automatically on reboot.

To use NTP:

Install NTP on the machines that will host Eucalyptus components.
```
yum install ntp
```
Open the /etc/ntp.conf file and add NTP servers, as in the following example.
```
server 0.pool.ntp.org
server 1.pool.ntp.org
server 2.pool.ntp.org
```
Save and close the file.
Configure NTP to run at reboot.
```
chkconfig ntpd on
```
Start NTP.
```
service ntpd start
```
Synchronize your server.
```
ntpdate -u <your_ntp_server>
```
Synchronize your system clock, so that when your system is rebooted, it does not get out of sync.
```
hwclock --systohc
```
Repeat on each host that will run a Eucalyptus component.