The ntpq utility is the tool to monitor the NTP daemon status. After configure NTP server you can use this tool to see the synchronization server status, and determine performance:
~ $ ntpq -pn
remote refid st t when poll reach delay offset jitter
==============================================================================
*217.114.59.66 75.12.230.181 2 u 127 128 377 8.786 -0.448 0.094
-193.225.118.163 228.143.95.23 2 u 70 128 377 36.129 -1.790 0.079
-46.22.223.220 129.242.4.241 2 u 52 128 377 40.330 3.975 0.055
+91.234.160.19 162.23.41.55 2 u 57 128 377 21.482 -0.364 0.093
127.127.1.0 .LOCL. 10 l 37m 64 0 0.000 0.000 0.000
remote column:
* : custom time server source
# : source selected, distance exceeds maximum value
o : the PPS (Pulse Per Second) source if you have a PPS capable system and refclock
+ : candidate, it is considered a good source
– : discarded, quality is not good
x : false ticker, this one is considered to distribute bad time
blank : source discarded, failed sanity or high stratum
refid column:
The identification of the time source to which the remote machine is synced. May be a radio clock or another ntp server.
st column:
Stratum of the remote machine, 16 is “unsynchronized”, 0 is the best value. A stratum 0 could be a radio clock or the ntp servers private caesium clock.
t column:
l = local (such as a GPS, WWVB)
u = unicast (most common)
m = multicast
b = broadcast
– = netaddr
when column:
Seconds since the last poll of the remote machine.
poll column:
The polling interval in seconds.
reach column:
Connections to reach source, 377 means all connections got success.
delay column:
The time delay (in milliseconds) to communicate with the remote source.
offset column:
The offset (in milliseconds) between our time and that of the remote source.
jitter column:
The observed difference (in milliseconds) of time with the remote source.