Product Documentation

Configuring Clock Synchronization

Aug 23, 2013

You can configure your NetScaler appliance to synchronize its local clock with a Network Time Protocol (NTP) server. This ensures that its clock has the same date and time settings as the other servers on your network. NTP uses User Datagram Protocol (UDP) port 123 as its transport layer. You have to add NTP servers in the NTP configuration file so that the appliance periodically gets updates from these servers.

If you do not have a local NTP server, you can find a list of public, open access, NTP servers at the official NTP site at

To configure clock synchronization on your appliance

  1. Log on to the command line and enter the shell command.
  2. At the shell prompt, copy the ntp.conf file from the /etc directory to the /nsconfig directory. If the file already exists in the /nsconfig directory, make sure that you remove the following entries from the ntp.conf file:

    restrict localhost


    These entries are required only if you want to run the device as a time server. However, this feature is not supported on the NetScaler.

  3. Edit /nsconfig/ntp.conf by typing the IP address for the desired NTP server under the file’s server and restrict entries.
  4. Create a file named rc.netscaler in the /nsconfig directory, if the file does not already exist in the directory.
  5. Edit /nsconfig/rc.netscaler by adding the following entry: /usr/sbin/ntpd -c /nsconfig/ntp.conf -l /var/log/ntpd.log &

    This entry starts the ntpd service, checks the ntp.conf file, and logs messages in the /var/log directory.

    Note: If the time difference between the NetScaler and the time server is more than 1000 sec, the ntpd service terminates with a message to the NetScaler log. To avoid this, you need to start ntpd with the -g option, which forcibly syncs the time. Add the following entry in /nsconfig/rc.netscaler:

    /usr/sbin/ntpd -g -c /nsconfig/ntp.conf -l /var/log/ntpd.log &

    If you do not want to forcibly sync the time when there is a large difference, you can set the date manually and then start ntpd again. You can check the time difference between the appliance and the time server by running the following command in the shell:

    ntpdate -q <IP address or domain name of the NTP server>
  6. Reboot the appliance to enable clock synchronization.
    Note: If you want to start time synchronization before you restart the appliance, enter the following command (which you added to the rc.netscaler file in step 5) at the shell prompt:
    /usr/sbin/ntpd -c /nsconfig/ntp.conf -l /var/log/ ntpd.log &