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Man page of ntpdc
ntpdc
Section: Maintenance Commands (8)
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NAME
ntpdc - monitor operation of the NTP daemon, ntpd
SYNOPSIS
/usr/bin/ntpdc
[
-n
][
-v
]
host1 | IPaddress1 ...
DESCRIPTION
The ntpdc command may be retired is a future release; use the
xntpdc(8) command instead.
The ntpdc
command sends a query to the ntpd
daemon running on each of the hosts listed on the command line.
The ntpd daemon on each responding host sends information about the
current calculated offset between its time and the time of each of
its NTP servers or peers. The ntpdc command formats
the information on the standard output.
The ntpdc program cannot be used to monitor the xntpd
daemon. To monitor the xntpd daemon, use either ntpq or
xntpdc.
Note
-
You can specify hosts by either host name or Internet
address. The hosts that you specify must either exist
in the /etc/hosts file, or in the master hosts
database, if the database is being served to your
system by BIND or Network Information Services (NIS).
The ntpdc command by default generates a terse, table-style report.
If you
specify the -v option, the ntpdc command generates
a verbose report.
FLAGS
- -n
-
Prints Internet addresses, instead of host names, of the
servers or peers.
By default, the Internet addresses of the responding hosts and the
names of their servers or peers are
printed.
- -v
-
Prints a verbose report for each of the servers or peers
of the responding host.
EXAMPLES
Terse Report:
The following is a typical terse report generated in response to the
command:
% /usr/bin/ntpdc 555.5.55.55
The host 555.5.55.55 is an NTP client, with the servers server1,
server2, and server3 specified in its
/etc/ntp.conf file. The information returned is about
server1, server2, and server3.
Address Strat Poll Reach Delay Offset Disp
(rem) (lcl)
.server1 555.5.55.55 1 64 377 53.0 -65.0 5.0
*server2 555.5.55.55 1 256 377 155.0 -4.0 16.0
+server3 555.5.55.55 2 64 377 16.0 -61.0 3.0
The fields are interpreted as follows:
- - , + , . or *
-
A minus sign (-), plus sign (+), or dot (.) indicates a
pre-configured peer (see the ntp.conf(4) reference page).
The asterisk (*) indicates which pre-configured peer (if
any) is currently being used for synchronization.
- (rem)
-
The remote host name or Internet address of a peer or server of the
responding host.
- (lcl)
-
The Internet address of the responding host that was specified on the
ntpdc command line.
- Strat
-
The current operating stratum level of the peer
or server. Since the NTP hierarchy can change dynamically the stratum
levels may change. Lower stratum levels correspond to fewer hops to an
accurate time source, and do not necessarily correspond to higher accuracy.
- Poll
-
Current polling interval in seconds for this peer or server.
Polling intervals change dynamically.
- Reach
-
Reachability in response to the last 8 polls (value of
8-bit shift register). A value of 0377 indicates the remote system
responded to the last 8 polls.
- Delay
-
The estimated round-trip delay in milliseconds for
NTP message exchanges between the responding host and this peer
or server. Delay is calculated from the previous 8 polls.
- Offset
-
The estimated offset between the peer or server's time and the responding
host's time in milliseconds. This value is calculated from the
previous 8 polls.
- Disp
-
The current estimated value of dispersion in milliseconds for this peer's
offset/delay pair.
-
Dispersion is used by the ntpd
daemon in the clock selection algorithm. Increasing values of dispersion are
associated with decreasing quality of the estimate.
Verbose Report:
When the -v option is given,
a verbose report for each of the servers or peers
of each of the hosts
specified on the command line is generated.
The following is a typical verbose report generated in response to the
following command line:
% /usr/bin/ntpdc -v 111.11.111.11
Neighbor address 555.55.5.55 port:123 local address 111.11.1.11
Reach: 0377 stratum: 2, precision: -7
dispersion: 2.000000, flags: 1301, leap: 0
Reference clock ID: [22.22.2.22] timestamp: 7e5aa1a9.2add5d0b
hpoll: 10, ppoll: 10, timer: 1024, sent: 85 received: 90
Delay(ms) 20.00 20.00 28.00 29.00 20.00 39.00 29.00 28.00
Offset(ms) 5.00 6.00 5.00 -1.00 -2.00 0.00 3.00 5.00
delay: 20.000000 offset: 5.000000 dsp 2.000000
--------------------------------------------------------------------
The fields are interpreted as follows:
- Neighbor address
-
The address and port number of one NTP server, followed by
the Internet address of the responding host (local address).
- Reach:
-
Reachability in response to the last 8 polls (value of
8-bit shift register). A value of 0377 indicates the remote system
responded to the last 8 polls.
- stratum:
-
The current operating stratum level of the peer
or server. Since the NTP hierarchy can change dynamically the stratum
levels may change. Lower stratum levels correspond to fewer hops to an
accurate time source, and do not necessarily correspond to higher accuracy.
- precision:
-
The precision of this clock, given in seconds as a power of
2. If precision is equal to
-7, that means that the precision is 2**-7, or 1/128 seconds.
The ntpd daemon automatically determines the
precision of each clock based on the
kernel variable HZ.
- disp:
-
The current estimated value of dispersion in milliseconds for this peer's
offset/delay pair.
Dispersion is used by the ntpd
daemon in the clock selection algorithm. Increasing values of dispersion are
associated with decreasing quality of the estimate.
- flags: nn
-
The flags parameter is used by the ntpd
daemon clock selection process.
- leap: flag
-
The leap second indicator. Non-zero if there is to be a
leap second inserted in the NTP timescale. The bits are
set before 23:59 on the day of insertion and reset after
00:00 on the following day.
- Reference clock ID: address
-
If the NTP server is synchronized by a radio/satellite
timecode receiver, this field is WWV, WWVB, or GOES.
If the NTP server is the local reference clock, this field is LOCL.
Finally, this field can be the [internet_address]
of the most accurate NTP server currently serving the responding
host.
- timestamp: nn
-
The local time, in hex-timestamp format, when the local clock
of the server was last updated.
- hpoll: n
-
The host poll interval which is the maximum interval between messages
transmitted to the server, in seconds as a power of 2. For
example, a value of 6 indicates an interval of 64 seconds.
- ppoll: n
-
The peer poll interval which is the maximum interval between messages
sent by the server, in seconds as a power of 2. For
example, a value of 6 indicates an interval of 64 seconds.
- timer: nn
-
The current poll rate in seconds.
- sent: nn
-
The number of NTP packets sent to this server by the responding host.
- received: nn
-
The number of NTP packets received from this server by the responding
host.
- Delay and Offset
-
The round-trip delay and estimated clock offset for the last eight NTP
packet exchanges. If there are fewer than eight valid samples,
the delay field will be zero.
- delay: est-delay offset: est-offset dsp: n
-
Estimated delay, offset, and dispersion calculated from the
above 8 samples. See RFC 1129 for how to calculate the
estimated delay, offset, and dispersion.
ERRORS
host1: connection refused
Check whether the ntpd daemon is running on host1.
host2: unknown
The ntpdc command cannot resolve the host name host2.
Check that host2 exists in the /etc/hosts
file, or that it exists in the master hosts
database, if the database is being served by BIND or NIS.
If a server is listed in the host's /etc/ntp.conf
file, but does not appear in the ntpdc
report, it is possible that the ntpd
daemon on the responding host can not resolve the server
names in the /etc/ntp.conf file. Check that the server
exists in the responding host's /etc/hosts file or in the master
hosts database, if the database is being served
to the responding host by BIND or NIS.
RELATED INFORMATION
ntp(1), ntp.conf(4), ntpq(8),
ntpsetup(8), xntpdc(8), xntpd(8)
RFC 1129---Internet Time Synchronization: the Network Time Protocol
Network Administration
Network and Communications Overview
delim off
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- FLAGS
-
- EXAMPLES
-
- Terse Report:
-
- Verbose Report:
-
- ERRORS
-
- RELATED INFORMATION
-
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Time: 02:40:33 GMT, October 02, 2010