Check manual page of ntp
This check uses the output of ntpq -p as sent by the agent. It is
a list of all NTP peers with their state, stratum, offset and jitter.
The check gets critical if the time offset exceeds a configurable level,
if the stratum is too high or on othe error conditions. It gets UNKNOWN
if the peer is unreachable or has not answered for a long time.
Note: This check creates one individual service for each peer. It is useful
for monitoring the health of the peers. If you want to monitor only the
time of the NTP client, you might rather use ntp.time.
The name or IP address of the peer (first column in output of ntpq -p.
Checks are created for all peers which have been contacted at least once,
if ntp_inventory_mode is set to "detailed" or "both". In case
of "summary" a check of type ntp.time is being created.