Installing and Administering Internet Services

228 Chapter 7

Conﬁguring NTP

Querying xntpd

ntpq is a program used to query systems that are running xntpd about

the current state of the server. It can also be used to obtain a list of a

server’s peers. ntpq sends requests to and receives responses from NTP

time servers using a special form of NTP messages called mode-6

control messages. The program can be run either interactively or from

a command line. See the ntpq man page for details about using this

program.

ntpq is most useful for querying remote NTP implementations to assess

their timekeeping accuracy and to expose problems in conﬁguration or

operation.

NOTE When you specify time-related conﬁguration options in /etc/ntp.conf,

you specify the values in seconds. ntpq, however, displays time values in

milliseconds, as speciﬁed by the RFC 1305 NTP standard.

Use ntpq to verify the following:

• xntpd can form associations with other NTP hosts.

• Synchronization is taking place correctly.

After xntpd starts, run the ntpq program with the -p option:

/usr/sbin/ntpq -p

The -p option prints a list of NTP hosts known to the server, along with a

summary of their states. After a while, a display like the following

appears:

Figure 7-11 ntpg Output Showing Known NTP Hosts

The remote column shows hosts speciﬁed in the local host’s

conﬁguration ﬁle plus other hosts that are conﬁgured to be peers with

the local host. The host address preceded with a ‘*’ indicates the current

remote refid st when poll reach delay offset disp

=======================================================================

+node1 node3 2 131 256 373 9.89 16.28 23.25

*server1 .WWVB. 1 137 256 377 280.62 21.74 20.23

-node2 node4 2 49 128 376 294.14 5.94 17.47

+server2 .WWVB. 1 173 256 377 279.95 20.56 16.40