Manually Configuring Ntp In The Network; Setting Up A Local Reference Clock - Novell LINUX ENTERPRISE SERVER 11 - ADMINISTRATION Administration Manual

20.2 Manually Configuring ntp in the
Network
The easiest way to use a time server in the network is to set server parameters. For ex-
ample, if a time server called ntp.example.com is reachable from the network, add
its name to the file /etc/ntp.conf by adding the following line:
server ntp.example.com
To add more time servers, insert additional lines with the keyword server. After
initializing ntpd with the command rcntp start, it takes about one hour until the
time is stabilized and the drift file for correcting the local computer clock is created.
With the drift file, the systematic error of the hardware clock can be computed as soon
as the computer is powered on. The correction is used immediately, resulting in a
higher stability of the system time.
There are two possible ways to use the NTP mechanism as a client: First, the client can
query the time from a known server in regular intervals. With many clients, this approach
can cause a high load on the server. Second, the client can wait for NTP broadcasts sent
out by broadcast time servers in the network. This approach has the disadvantage that
the quality of the server is unknown and a server sending out wrong information can
cause severe problems.
If the time is obtained via broadcast, you do not need the server name. In this case, enter
the line broadcastclient in the configuration file /etc/ntp.conf. To use one
or more known time servers exclusively, enter their names in the line starting with
servers.
20.3 Setting Up a Local Reference
Clock
The software package ntp contains drivers for connecting local reference clocks. A list
of supported clocks is available in the ntp-doc package in the file /usr/share/
doc/packages/ntp-doc/refclock.html. Every driver is associated with a
number. In ntp, the actual configuration takes place by means of pseudo IP addresses.
The clocks are entered in the file /etc/ntp.conf as though they existed in the net-
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