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, if necessary, 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.
Synchronize your server.
```
ntpdate -u YOUR_NTP_SERVER
```
Configure NTP to run at reboot.
```
systemctl enable ntpd.service
```
Start NTP.
```
systemctl start ntpd.service
```
Synchronize your system clock, so that when your system is rebooted, it does not get out of sync.
```
hwclock --systohc
```
Repeat on each host machine that will run a Eucalyptus service.