HP-UX Internet Services Administrator's Guide (August 2003)

Configuring NTP
Getting Started with NTP
Chapter 4 71
server ntp-cup.external.hp.com
server bigben.cac.washington.edu
server sirius.ctr.columbia.edu
Backup Time Servers
After selecting the primary time server, you must select two additional
time servers that serve as backup time servers. The closest and fastest
time server must be the primary time server. Backup time servers act as
stand-by servers when the primary time server is not available. The
process of establishing backup servers is known as employing
redundancy. Backup time servers ensure that time sensitive applications
have an alternative reliable source for time synchronization.
NOTE You should select at least three backup servers for redundancy.
The NTP Daemon
The daemon, xntpd, is the network time protocol daemon. It is an
operating system daemon that sets and maintains the system time in
synchronization with the Internet standard time servers. xntpd is an
implementation of NTP Version 3, as defined in RFC1305 (Network Time
Protocol Version 3 – Specification and Implementation). It is also
compatible with the NTP servers Version 1 and 2 as defined in RFC 1059
(Network Time Protocol Version 1 – Specification and Implementation)
and RFC 1119 (Network Time Protocol Version 2 – Specification and
Implementation), respectively.
xntpd operates in the following modes: symmetric active, symmetric
passive, client/server, broadcast, and multicast mode, as specified in RFC
1305. Abroadcast or multicast client can deploy a group of workstations
without specifying configuration details specific to the local environment
A broadcast or multicast client can perform the following functions:
• Discover remote server.
• Compute client/server propagation delay correction factors.
• Configure itself automatically.