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22.13. Checking the Status of NTP
To check if
ntpd is configured to run at system start, issue the following command:
~]$ chkconfig --list ntpd
ntpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
By default, when ntpd is installed, it is configured to start at every system start.
To check if
ntpd is running, issue the following command:
~]$ ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
+clock.util.phx2 .CDMA. 1 u 111 128 377 175.495 3.076 2.250
*clock02.util.ph .CDMA. 1 u 69 128 377 175.357 7.641 3.671
ms21.snowflakeh .STEP. 16 u - 1024 0 0.000 0.000 0.000
rs11.lvs.iif.hu .STEP. 16 u - 1024 0 0.000 0.000 0.000
2001:470:28:bde .STEP. 16 u - 1024 0 0.000 0.000 0.000
The command lists connected time servers and displays information indicating when they were last polled and the stability of the replies. The column headings are as follows:
- remote and refid: remote NTP server, and its NTP server
- st: stratum of server
- t: type of server (local, unicast, multicast, or broadcast)
- poll: how frequently to query server (in seconds)
- when: how long since last poll (in seconds)
- reach: octal bitmask of success or failure of last 8 queries (left-shifted); 377 = 11111111 = all recent queries were successful; 257 = 10101111 = 4 most recent were successful, 5 and 7 failed
- delay: network round trip time (in milliseconds)
- offset: difference between local clock and remote clock (in milliseconds)
- jitter: difference of successive time values from server (high jitter could be due to an unstable clock or, more likely, poor network performance)
To obtain a brief status report from
ntpd, issue the following command:
~]$ ntpstat
unsynchronised
time server re-starting
polling server every 64 s
~]$ ntpstat
synchronised to NTP server (10.5.26.10) at stratum 2
time correct to within 52 ms
polling server every 1024 s
