Explanation References: "In this case, your security rules might not include the IP range for the source of the health check requests. You can find the health check source IP on the Details page for each backend server. You can also use the API to find the IP in the sourceIpAddress field of the HealthCheckResult object." https://docs.cloud.oracle.com/iaas/Content/Balance/Tasks/editinghealthcheck.htm#health-status