Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 11-05-2007, Installation Manual

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32
Time Synchronization with
NTP
The NTP (network time protocol) mechanism is a protocol for synchronizing the system
time over the network. First, a machine can obtain the time from a server that is a reliable
time source. Second, a machine can itself act as a time source for other computers in
the network. The goal is twofold—maintaining the absolute time and synchronizing
the system time of all machines within a network.
Maintaining an exact system time is important in many situations. The built-in hardware
(BIOS) clock does often not meet the requirements of applications like databases.
Manual correction of the system time would lead to severe problems because, for ex-
ample, a backward leap can cause malfunction of critical applications. Within a network,
it is usually necessary to synchronize the system time of all machines, but manual time
adjustment is a bad approach. xntp provides an mechanism to solve these problems. It
continuously adjusts the system time with the help of reliable time servers in the network.
It further enables the management of local reference clocks, such as radio-controlled
clocks.
32.1 Configuring an NTP Client with
YaST
xntp is preset to use the local computer clock as a time reference. Using the (BIOS)
clock, however, only serves as a fallback for the case that no time source of greater
precision is available. YaST facilitates the configuration of an NTP client. For a system
that is not running a firewall, use either the quick or advanced configuration. For a
Time Synchronization with NTP 603