Oracle Cloud Infrastructure 2019 Developer Associate — Question 148

You are an administrator with an application running in Oracle Cloud Infrastructure (OCI). The company has a fleet of OCI compute virtual instances behind a load balancer. The load balancer backend set health check API is providing a "˜Critical' level warning. You have confirmed that your application is running healthy on the backend servers.
What is the possible reason for this "˜Critical' warning?

Answer options

• A. The load balancer listener is not configured correctly.
• B. A user does not have correct Identity and Access Management (IAM) credentials on the backend servers.
• C. The security list associated with the subnet in which the backend server is provisioned does not include the IP range for the source of the health check requests.
• D. The route table associated with the subnet in which the backend server is provisioned does not include the route for OCI load balancer.

Correct answer: C

Explanation

The correct answer is C because if the security list does not allow the IP range of the health check requests, the load balancer cannot communicate with the backend servers to verify their health, resulting in a 'Critical' warning. Option A is incorrect because even if the listener is misconfigured, it wouldn't lead to a health check warning if the application is healthy. Option B is also not relevant since IAM credentials do not affect health checks. Option D is wrong because a route table issue would typically cause broader connectivity problems, not just health check failures.