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NTPD(8)			    System Manager's Manual		       NTPD(8)

NAME
       ntpd - time synchronization daemon implementing NTP

SYNOPSIS
       /usr/etc/ntpd [-a threshold] [-l] [-n] [-s]

OPTIONS
       -a  threshold  is used to set the threshold, limiting how far ntpd will
       change the system clock.	 It is used to prevent the  system  time  from
       being changed a great deal.  By default,	the threshold is 1000 seconds.
       The threshold is	to be specified	in units of seconds, or	the string any
       to defeat the sanity check.

       -l  will	 cause	ntpd  to  log a	message	each time the logical clock is
       changed.	 Normally, do not specify this option except to	gather statis-
       tical  information for analyzing	the logical clock behavior.  If	the -l
       option is specified, a message will be  logged  approximately  every  2
       minutes.

       -s will prevent ntpd from adjusting the local clock.

DESCRIPTION
       The  ntpd  network  time	 synchronization daemon	is normally invoked at
       boot time from the /etc/rc(8) file.  It implements the version  of  the
       Network	Time  Protocol described in RFC-1059.  It maintains the	host's
       time, synchronized with a set of	distributed time  servers,  each  with
       varying accuracy	and reliability.  Multiple time	server masters may ex-
       ist, but	there is no requirement	for election of	a single master.

       The ntpd	daemon uses adjtime(2) to adjust the clock of the  host	 by  a
       small  amount  in  order	 to keep the clock synchronized.  If the local
       clock exceeds the ``correct'' time by some threshold,  then  settimeof-
       day(2) is used to make a	step adjustment	of the local clock.

       When ntpd(8) is started on the machine, it reads	configuration informa-
       tion from netinfo, which	contains  information  about  other  ntp  time
       servers	and  host  specific information.  Configuration	information is
       created and managed by the HostManager application.

       The driftfile command can be used to specify the	name of	the file  from
       which  the drift	compensation register will be loaded at	initialization
       time, and to which updated values will be written.  The drift compensa-
       tion  value  describes  the  intrinsic drift of the host	clock.	By de-
       fault, the file /etc/ntp.drift is used.

       Currently, three	time  server  specifications  are  supported:  master,
       clone and client.

       It  is  recommended  that the bulk of the machines configured should be
       clients,	as this	will  minimize	resource  demand  on  the  remote  NTP
       server.	 If  the  host will be serving as a redistribution point for a
       cluster of hosts, it should be set up as	 a  clone  or  master  server.
       Configuration of	servers	is accomplished	through	the HostManager	appli-
       cation.

NOTES
       Please choose NTP servers carefully.

BUGS
       No doubt.

FILES
       /etc/ntp.drift  Stores local machines drift parameters.

SEE ALSO
       adjtime(2), settimeofday(2),
       RFC-1059	Network	Time Protocol(1), Mills, D.L.

AUTHORS
       Louis A.	Mamakos, louie@TRANTOR.UMD.EDU
       Michael G. Petry, petry@TRANTOR.UMD.EDU
       The University of Maryland Computer Science Center.

ADAPTATION TO NEXT AND NETINFO
       Lee T. Tucker, NeXT Computer, Inc.

				9 December 1988			       NTPD(8)

NAME | SYNOPSIS | OPTIONS | DESCRIPTION | NOTES | BUGS | FILES | SEE ALSO | AUTHORS | ADAPTATION TO NEXT AND NETINFO

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