Cisco DNCS System Release 2.7 3.7 4.2 Guía De Instalación
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Configure an NTP Server
78-4011510-01 Rev C
Configure an NTP Server
Introduction
NTP servers are an alternative to using the GPS for system time synchronization. If a
site is unable to use the GPS, they may elect to use an NTP server. NTP servers are
located throughout the world and are accessible using the Internet. This section
contains procedures for installing, verifying, and monitoring an NTP server on the
DNCS.
You can choose to utilize a single NTP server or multiple NTP servers. With multiple
You can choose to utilize a single NTP server or multiple NTP servers. With multiple
NTP servers, the NTP daemon queries all the NTP sources. The delay between the
sources is calculated and the NTP daemon averages them out to obtain an accurate
time. If one NTP server becomes unresponsive, the NTP daemon does not use it to
calculate time. When the unresponsive server returns to service, the NTP daemon
will once again use it to calculate time.
Before You Begin
To configure your DNCS to use an NTP server, you will first need to identify an NTP
server. Then, you will need to work with your Network Administrator to configure
the DNCS to communicate with that time server.
You should also configure an additional NTP server in the unlikely event that you
You should also configure an additional NTP server in the unlikely event that you
lose communication with the primary NTP server (usually the VPN connection) for
an extended period of time. To configure an additional NTP server, locate an NTP
server and verify the network connectivity and status of the server using the ntpdate
command and the IP address of the additional server. Then, add the entry to both
the /etc/hosts file and the NTP configuration file as you configure your primary
NTP server.
Locating an NTP Server
The easiest NTP server to use is the router that is set up for VPN access to the DNCS.
Alternatively, there are many places to find NTP servers. A good place to start is the
following URL: http://ntp.isc.org/bin/view/Servers/StratumOneTimeServers. Or,
you can access the parent site of the previous URL at http://www.ntp.org to locate an
alternate NTP server.
Note: You need to add entries to the /etc/hosts file to allow the DNCS to resolve
Note: You need to add entries to the /etc/hosts file to allow the DNCS to resolve
the name.
Installing an NTP Server
Complete these steps to install an NTP server on your system.
1.
Obtain the IP address of the NTP server to be used for the DNCS.
Important: The DNCS must have a network connection to the NTP server in
Important: The DNCS must have a network connection to the NTP server in
order to receive time messages from the NTP server.
2.
Click the DNCS tab from the DNCS Administrative Console window; then
click the Utilities tab.