freebsd/usr.sbin/ntp/doc/ntptrace.8

.\"
.\" $FreeBSD$
.\"
.Dd January 6, 2000
.Dt NTPTRACE 8
.Os
.Sh NAME
.Nm ntptrace
.Nd "trace a chain of NTP servers back to the primary source"
.Sh SYNOPSIS
.Nm
.Op Fl vdn
.Op Fl r Ar retries
.Op Fl t Ar timeout
.Op Ar server
.Sh DESCRIPTION
The
.Nm
utility determines where a given Network Time Protocol (NTP) server gets
its time from, and follows the chain of NTP servers back to their
master time source.
If given no arguments, it starts with
.Dq localhost .
.Pp
Here is an example of the output from
.Nm :
.Bd -literal
% ntptrace
localhost: stratum 4, offset 0.0019529, synch distance 0.144135
server2ozo.com: stratum 2, offset 0.0124263, synch distance 0.115784
usndh.edu: stratum 1, offset 0.0019298, synch distance 0.011993, refid 'WWVB'
.Ed
.Pp
On each line, the fields are (left to right): the host name, the
host stratum,
the time offset between that host and the local host
(as measured by
.Nm ;
this is why it is not always zero for
.Dq localhost ) ,
the host
synchronization distance,
and (only for stratum-1 servers) the reference clock ID.
All times
are given in seconds.
Note that the stratum is the server hop count to the primary source,
while the synchronization distance is the estimated error
relative to the primary source.
These terms are precisely defined in RFC 1305.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl d
Turn on some debugging output.
.It Fl n
Turn off the printing of host names; instead, host IP addresses
are given.
This may be necessary if a nameserver is down.
.It Fl r Ar retries
Set the number of retransmission attempts for each host; the default is 5.
.It Fl t Ar timeout
Set the retransmission timeout (in seconds); the default is 2.
.It Fl v
Print verbose information about the NTP servers.
.El
.Sh SEE ALSO
.Xr ntpd 8 ,
.Xr ntpdc 8
.Rs
.%A D L Mills
.%T Network Time Protocol (Version 3)
.%O RFC1305
.Re
.Sh BUGS
This program makes no attempt to improve accuracy by doing multiple
samples.