HP-UX Internet Services Administrator's Guide (May 2010)

be synchronized close to 1000 milliseconds, to ensure that make compiles the appropriate
files.
The following topics are discussed in this section:
• “NTP Equipment” (page 46)
• “Choosing the Source of Time” (page 46)
• “Backup Time Servers” (page 55)
• “Configuring Your Primary NTP Server” (page 56)
NTP Equipment
The following equipments are required to effectively use the NTP programs:
• Internet or your own radio receiver, such as GPS (Global Positioning System), as
a time source.
• An ordinary network, such as an Ethernet, in your building.
• Familiarity with configuring and setting up NTP.
Starting NTP Configuration
For a basic NTP configuration, you must complete the following steps:
1. Choose a source of time.
2. Determine how frequently the system clock must synchronize with the source of
time.
3. Select backup time server.
4. Configure the primary NTP server.
The following sections cover these steps in detail.
Choosing the Source of Time
Government organizations define, regulate and distribute time for synchronization
purpose. These organizations constantly coordinate and synchronize their clocks with
other organizations within nanoseconds of each other. The first step in using NTP is
selecting the best source of time for your organization.
You must be careful while selecting the source of time. If the type of applications and
processes the users run are sensitive to time, you must select the source of time that
provides a stable time, and is not affected by network delays. Do not select the NTP
service depending on price.
Also, select a source of time that you can reach fast. The closer the source of time, the
better. Choose a source that is physically close and one that takes few network hops
to reach the destination. For more information on physical and network distance, see
“Configuring Mulltiple Time Servers” on page 221.
46 Configuring NTP