ntpdc(8) System Manager's Manual ntpdc(8)
Name
ntpdc - monitor operation of the NTP daemon, ntpd
Syntax
/usr/etc/ntpdc [ -n ][ -v ] host1 | IPaddress1 ...
Description
The command sends a query to the daemon running on each of the hosts listed on the command line. The 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 command formats the
information on the standard output.
You can specify hosts by either host name or Internet address. The hosts that you specify must either exist in the file, or in the master
database, if the database is being served to your system by BIND/Hesiod or Yellow Pages. The command by default generates a terse, table-
style report. If you specify the option, the command generates a verbose report.
Options
-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/etc/ntpdc 555.5.55.55
The host 555.5.55.55 is an NTP client, with the servers and specified in its file. The information returned is about and
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 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 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 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 with bits entering from the end furthest to the right).
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 daemon in the clock selection algorithm. Increasing values of dispersion are associated with decreasing
quality of the estimate.
Verbose Report:
When the option is given, a verbose report for each of the servers or peers of each of the hosts specified on the command line is gener-
ated.
The following is a typical verbose report generated in response to the following command line:
% /usr/etc/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 with bits entering from the end furthest to the right).
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 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 daemon automatically determines the precision of each clock based on the kernel variable
disp: The current estimated value of dispersion in milliseconds for this peer's offset/delay pair. Dispersion is used by the daemon in
the clock selection algorithm. Increasing values of dispersion are associated with decreasing quality of the estimate.
flags: nn
The parameter is used by the 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 or If the NTP server is the local reference
clock, this field is Finally, this field can be the 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 sam-
ples, 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.
Diagnostics
host1: connection refused
Check whether the daemon is running on
host2: unknown
The command cannot resolve the host name Check that exists in the file, or that it exists in the master database, if the database is being
served by BIND/Hesiod or Yellow Pages.
If a server is listed in the host's file, but does not appear in the report, it is possible that the daemon on the responding host can not
resolve the server names in the file. Check that the server exists in the responding host's file or in the master database, if the data-
base is being served to the responding host by BIND/Hesiod or Yellow Pages.
See Also
ntp.conf(5), ntp(8), ntpd(8)
RFC 1129--Internet Time Synchronization: the Network Time Protocol
Introduction to Networking and Distributed System Services
ntpdc(8)