Thursday, May 26, 2011

Explanation of the output of the "ntpq -p" command ?

■ Requirement : Explain output of  "ntpq -p"
■ OS Environment : Linux[RHEL, Centos]
■ Application: ntpq
■ Resolution  : 

$ ntpq -p

remote refid st t when poll reach delay offset jitter

* LOCAL(0) 11 u 186 512 377 123.355 45.573 8.832

Columns Defined:
remote: peers specified in the ntp.conf file
* = current time source
# = source selected, distance exceeds maximum value
o = source selected, Pulse Per Second (PPS) used
+ = source selected, included in final set
x = source false ticker
. = source selected from end of candidate list
- = source discarded by cluster algorithm
blank = source discarded high stratum, failed sanity

refid: remote source’s synchronization source
stratum: stratum level of the source

t: types available
l = local (such as a GPS, WWVB)
u = unicast (most common)
m = multicast
b = broadcast
- = netaddr

when: number of seconds passed since last response
poll: polling interval, in seconds, for source
reach: indicates success/failure to reach source, 377 all attempts successful
delay: indicates the roundtrip time, in milliseconds, to receive a reply
offset: indicates the time difference, in milliseconds, between the client server and source
disp/jitter: indicates the difference, in milliseconds, between two samples

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