Oracle Cloud Infrastructure 2025 Developer Professional Advanced Practice Exam: Hard Questions 2025

You run a containerized microservice on OCI Container Engine for Kubernetes (OKE). It calls multiple OCI services (Object Storage, Streaming, and Secrets) and must not use long-lived user credentials. After migrating to instance principals, calls from some pods intermittently fail with "NotAuthorizedOrNotFound" while other pods succeed. The nodes are in a dynamic group that has the required policies. You also use a service mesh with sidecars and multiple node pools. What is the MOST likely root cause and the best fix?

A team is designing a zero-downtime deployment strategy for a stateless API on OKE behind an OCI Load Balancer. The API uses database connections and maintains an in-memory cache. During rolling updates, they occasionally see elevated 5xx responses and failed requests for in-flight calls. Readiness probes are configured, but not lifecycle hooks. Which combination of changes best minimizes failed requests during deployment while preserving fast rollout?

You operate a set of Functions that ingest events from OCI Streaming. During a traffic surge, you observe increasing function duration and rising error rates. Metrics show high throttling on the downstream Object Storage writes and occasional duplicate event processing. You must guarantee at-least-once processing with idempotency and control backpressure without losing events. Which architecture change best addresses these constraints?

Your CI/CD pipeline uses OCI DevOps to build and deploy to OKE. Builds intermittently fail when pushing images to OCI Container Registry (OCIR) with an authentication error. The DevOps build runner is in a private subnet and uses a NAT gateway for egress. IAM policies for the DevOps project and dynamic group appear correct. What is the MOST probable cause and the best fix?

A serverless application uses OCI API Gateway in front of OCI Functions. The backend function must call another internal service in a private subnet (not publicly routable). The API Gateway is currently configured with a public endpoint and backends are reachable, but calls from the function to the private service fail with timeouts. You must keep the API public while enabling private egress to the internal service. What is the best design?

A DevOps deployment pipeline applies Kubernetes manifests to multiple OKE clusters across compartments. The pipeline uses a single deployment stage with different environments. Sometimes, the stage fails with authorization errors when targeting a specific compartment even though the same stage works for others. You want least privilege and a predictable permission model. Which approach best meets these goals?

An event-driven workflow ingests SaaS events via OCI Integration Cloud (OIC), transforms them, and publishes to OCI Streaming for downstream microservices. During a regional network disruption, OIC retries and Streaming consumers also retry, leading to message amplification and out-of-order effects. You must ensure downstream services can process reliably with minimal duplicates and bounded retry storms. Which design is BEST?

You have two microservices communicating via OCI Queue. Service A enqueues tasks; Service B dequeues and calls an external payment provider. After a partial outage, you find some payments were charged twice even though Queue visibility timeouts and retries are configured. You must prevent double-charge while keeping at-least-once delivery semantics. What is the most appropriate mitigation?

A workflow uses OCI Events to route Object Storage "ObjectCreated" events to an OCI Function that parses files and publishes results to Streaming. You notice that for multi-part uploads and certain client SDKs, you sometimes get multiple events for what appears to be a single logical file, and occasional missing downstream records. You need a robust design that tolerates event duplication and eventual consistency. Which solution is BEST?

An OKE-hosted service is experiencing sporadic latency spikes only under high concurrency. Application logs show no errors. You use OCI Logging, Monitoring, and APM Tracing. Traces show long gaps between spans with no child spans, and node metrics show occasional CPU throttling. You suspect Kubernetes resource limits and GC pauses, but need to prove it and identify whether throttling is at the container cgroup level or upstream network. What is the best next step using OCI observability tooling and Kubernetes signals?