Configuring time on existing Citrix Xenserver

When installing a Xenserver using the standard GUI, you will get to select Using NTP or Manual time entry. If you choose to use Manual time entry, or like to switch to another NTP server for some reasons, you will need to amend the configuration file (/etc/ntp.conf).

To do so, go to the server console either via Xencenter or physically on the server.

(I will use NANO editor for simplicity, you may use VI or any application to make the same changes)

1. To edit the configuration file:
nano /etc/ntp.conf

2. Add in the NTP server address, use {PGDN} to go to the last line of the configuration file:
Server configured here is the internal NTP, you may use 0.pool.ntp.org, 1.pool.ntp.org, 2.pool.ntp.org for the standard NTP servers (Refer to ntp.org for localized pools)
server 192.168.0.1


3. Save the changes by pressing {CTRL+X}, then type {Y}

4. Press {ENTER} to confirm

5. Restart NTPD to get the time synchronized:
/etc/init.d/ntpd restart

Refer: http://support.citrix.com/article/CTX116454