Installing and Administering Internet Services

Chapter 7 303

Conﬁguring the Network Time Protocol (NTP)

Advanced NTP Topics

NOTE Every node in an NTP hierarchy must have either a server statement or

a broadcastclient yes statement in its conﬁguration ﬁle. Every node

must have an upper-level server. A stratum-1 server must also have a

server statement in its conﬁguration ﬁle, which speciﬁes a radio clock or

internal system clock as a time source.

Note that if the local host is to assume the role of a server in providing

time to clients, there is no conﬁguration of this role on the local system.

Instead, the conﬁguration ﬁle on the client system would contain a

server statement with the name or IP address of the host.

Also note that if authentication is enabled on the local host, the roles you

conﬁgure are subject to the authentication process. For example, the

local host can be conﬁgured as a peer or a client of a stratum-1 server,

but if the remote server does not meet the criteria for an authenticated

synchronization source, it will never be used as a time source by the local

host. See “Conﬁguring Authentication” on page 305.

NOTE xntpd is an HP implementation of version 3.2 of a publicly-available

NTP daemon. HP does not guarantee that xntpd is fully compatible with

version 1 or version 2 implementations of the daemon.

Conﬁguring External Clocks

You can conﬁgure xntpd to support an external clock. Clocks are

normally conﬁgured with server statements in the conﬁguration ﬁle.

You can place the clock address can be used anywhere else in the

conﬁguration ﬁle.

Clocks are referenced by an address of the format 127.127.

, where

speciﬁes the clock type, and

is a unit number, which is dependent on

the clock type for interpretation (this allows multiple instances of the

same clock type on the same host).

xntpd supports two kinds of clocks:

• Netclock/2 WWVB Synchronized Clock. A system with this type of

clock attached and conﬁgured is, by deﬁnition, a stratum-1 time

server. The address used to conﬁgurethe clock is 127.127.4.

, where