ntp is just a wrapper around the ntptrace binary. You just can customize the errorlevel and the path to ntptrace. By default, the ntp check looks in /usr/bin, /usr/sbin, /sbin, /usr for the ntptrace binary. If the binary is somewhere else, you have to specify the path by the common tag "COMMAND". It is also possible to use sudo through the "command" tag.
All default tags (example: RUNIF_*) are supported, too
NTP is the enclosing tag for all ntp entries.
COMMAND . You may want to use something like sudo.
The common XML tags as described in Section 9.8, “Tags Common to All Checks and/or Checkpoints”
0 or 1. If you don't define NTP, no ntp check will run.
<NTP>
<ERRORLEVEL>WARNING</ERRORLEVEL>
<COMMAND>/usr/sbin/ntptrace</COMMAND>
</NTP>