Technical data

Configuring and Managing NTP
12.3 Configuring Your NTP Host
# The following commands allow this node to act as a backup NTP server (or as
# the sole NTP server on an isolated network), using its own system clock as
# the reference source. If enabled (by removing #), this NTP server will
# become active only when all other normal synchronization sources are
# unavailable.
# server 127.127.1.0
# fudge 127.127.1.0 stratum 8
12.3.3 Using NTP with Another Time Service
A local host may run more than one time service. For example, a host may have
both NTP and DTSS (Digital Time Synchronization Service) installed. However,
only one of these time services is allowed to set the system clock.
If you are running a time service in addition to NTP, you must stop either the
other time source or NTP from setting the system clock. You can stop NTP from
setting the system clock by adding the following statements to the configuration
file:
server 127.127.1.0 prefer
fudge 127.127.1.0 stratum 0
In these statements, the hardware address of the local clock (LOCAL) is
127.127.1.0. These statements force NTP to use its own system clock as a
reference clock. The host continues to respond to NTP time queries but does
not make any adjustments to the system clock, thereby allowing the other time
service to make those changes.
12.4 Configuring NTP as Backup Time Server
You can configure the NTP service as a backup time server. In this case, if all
other network synchronization sources become unavailable, the NTP service
becomes active. You can also use this method to allow the local node to act as
the NTP server in an an isolated network. To configure the NTP service as the
backup server or the sole NTP server, enter the following commands in the NTP
configuration file:
server 127.127.1.0
fudge 127.127.1.0 stratum 8
In this example, the stratum is set to a high number (8) so that it will not
interfere with any other, possibly better, time synchronization source. You should
set the stratum to a number that is higher than the stratum of all other time
synchronization sources.
12.5 Operating with Time Zone Offsets
The operating system’s installation procedure provides a command
procedure that defines a time zone differential (offset) logical name in
the system logical name table (LNM$SYSTEM_TABLE). The procedure
is SYS$EXAMPLES:DAYLIGHT_SAVINGS.COM. The logical name is
SYS$TIMEZONE_DIFFERENTIAL.
To change the time zone differential offset, follow these steps:
1. Make sure the following logical name is defined:
SYS$TIMEZONE_DIFFERENTIAL
This logical name is defined automatically when you install the OpenVMS
operating system.
Configuring and Managing NTP 12–9