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

Conﬁguring NTP

Advanced NTP Topics

Chapter 4 75

Advanced NTP Topics

This section includes advanced NTP topics and is ideal for experienced

users. The following sections are covered in this section:

• “Stratum Levels and Time Server Hierarchy” on page 75

• “Conﬁguring NTP using the Conﬁguration File” on page 78

• “Starting and Stopping xntpd” on page 87

• “Using ntpq to Query Systems Running xntpd” on page 88

• “Troubleshooting NTP” on page 91

Stratum Levels and Time Server Hierarchy

An NTP synchronization subnet is a network of time-keeping

systems, called time servers. These time servers are a subset of the

systems on a network or an internetwork. Each time server synchronizes

its time with the the Universal Coordinated Time (UTC), and measures

the time difference between its local system clock and the neighboring

system clocks. These servers are automatically assigned stratum values,

which indicate how close the time server is to the time source.

Stratum-1 Time Servers

Time servers are organized into levels, or strata. Stratum-1 servers are

directly connected to an external time source. The stratum-1 server

relies on the external source of time to provide the correct time, and

synchronizes its system clock to that external time source. The external