appliance has one built-in monitor that can be used to monitor SMNP services:
SNMP monitor. It periodically checks the SNMP agent
on the service to which it is bound by sending a query for the enterprise
identification ID (OID) that you configure for monitoring. If the query is
successful, the service is marked UP. If the SNMP service finds the OID that
you specified, the query succeeds and the SNMP monitor marks the service UP. If
it does not find the OID, the query fails and the SNMP monitor marks service
Note: Monitor probes originate from the NetScaler IP (NSIP) address.