http://support.f5.com/kb/en-us/solutions/public/10000/200/sol10240.html

Observe the output with references on the fields presented in the previous table.

Example of a successful NTP peer server query

If the local ntpd process can communicate or attempts to communicate with a declared NTP peer server, the output from the ntpq command appears similar to the following example:

# ntpq -np

remote           refid      st t  when poll reach  delay  offset   jitter
==============================================================================
172.28.4.133    10.10.10.251      4 u   482 1024   377  0.815  -10.010   0.345

In the previous example, the remote server information (refid, stratum, delay, offset, jitter) displays, and this indicates that the servers are successfully exchanging information. The value of 377 in the reach column indicates that the server was successfully reached during each of the last eight attempts, and the value of 482 in the when column indicates that the last response was received from the remote peer 482 seconds ago, which is within the polling interval of 1024 seconds.

Example of a failed NTP peer server query

If the local ntpd process fails to communicate with an NTP peer server, the output from the ntpq command may appear similar to the following example:

# ntpq -np      remote           refid      st t when poll reach   delay  offset   jitter
==============================================================================
172.28.4.133     .INIT.          16 u    -   64    0    0.000   0.000  0000.00

Note: An st (stratum) of 16 means that the destination NTP server is unreachable or is not considered a viable candidate.

In this example, the remote server information (refid, stratum, delay, offset, jitter) is not available. The value .INIT. in the refid column indicates that NTP is initializing, and the server has not yet been reached. The value of 0 (zero) in the reach column indicates that the server has not been reached during any of the last eight attempts. The absence of a value in the when column indicates that no data has been received from the remote peer since the local ntpd process was started. The poll value of 64 is still at the MINPOLL value, which indicates that NTP was recently restarted.

Example of a successful NTP preferred peer server query

If the local ntpd process communicates or attempts to communicate with a declared preferred NTP peer server, the output from the ntpq command appears similar to the following example:

# ntpq -np

remote           refid      st t  when poll reach  delay  offset   jitter
==============================================================================
*172.28.4.133    10.10.10.251      4 u   482 1024   377  0.815  -10.010   0.345
+172.28.4.134    10.10.10.252      6 u   482 1024   179  0.215  -1.010    0.545

In the previous example, 172.28.4.133 is the preferred server, or current time source, and is designated by the * symbol.  Any remaining servers available for use are indicated by the + symbol. When initially configured, NTPd can take up to a few minutes to calculate and designate the current preferred time source.