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ntpdc(8) System Manager's Manual ntpdc(8) 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 respond- ing 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 moni- tor 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 re- port. 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-con- figured 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 lev- els 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 re- sponded 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 calcu- lated 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 al- gorithm. 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 gener- ated. 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 re- sponded 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 lev- els 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 deter- mines 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 esti- mate. 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 fol- lowing 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 re- sponding 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 esti- mated 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 ntpdc(8)