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

You are designing a hub-and-spoke network in OCI. The hub VCN has a DRG attached and provides on-prem connectivity. Three spoke VCNs are locally peered to the hub (LPG). Requirement: on-prem must reach all spokes, and spokes must not communicate with each other. You also need to minimize route-table complexity and prevent accidental transitive routing between spokes. Which design best meets the requirements?

A production VCN uses a Service Gateway for private access to Object Storage and a NAT Gateway for general internet egress. Instances in a private subnet can reach Object Storage over the service gateway, but intermittently they reach it via the NAT Gateway instead, causing unexpected egress logging and policy violations. The subnet route table currently has: 0.0.0.0/0 -> NAT Gateway, and an Object Storage service CIDR label route -> Service Gateway. What is the most likely cause and best fix?

You operate a public OCI Load Balancer with two backend sets (blue/green). You need zero-downtime deployments and must ensure that clients with long-lived HTTP/2 connections are not dropped during a backend switch. Which approach best satisfies this requirement?

A FastConnect private virtual circuit is up, BGP is established, and on-prem routes are received in OCI. However, instances in OCI cannot reach on-prem networks. You verify security lists/NSGs allow the traffic. Which misconfiguration is the most likely cause?

A security team requires that a private subnet’s instances can only be reached from a specific on-prem CIDR over FastConnect, and must not be reachable from any other VCNs attached to the same DRG. The network team wants to enforce this as close to routing as possible (not only via instance firewalls). Which solution is best?

You use OCI Network Load Balancer (NLB) for a high-throughput TCP service. After enabling a strict security posture, you observe sporadic resets for some clients during backend maintenance windows. Backends are removed from the backend set to patch them. What is the best mitigation strategy to reduce client impact while maintaining high throughput?

A company is migrating from multiple overlapping RFC1918 networks on-prem into OCI. They need private connectivity via FastConnect, but overlapping CIDRs between on-prem and an OCI VCN will remain for months. They must enable connectivity without renumbering and without exposing workloads to the public internet. What is the most appropriate OCI networking approach?

You have a VCN with multiple subnets using a single route table. A new requirement states that a specific subnet must send all 0.0.0.0/0 egress through a virtual firewall (a private IP in another subnet) while other subnets continue to use the NAT Gateway. After change, some instances in the forced-firewall subnet lose connectivity, and packet captures show traffic reaching the firewall but return traffic bypassing it. What is the most likely root cause and best fix in OCI terms?

Security operations wants to detect and investigate intermittent packet loss between two instances in different subnets within the same VCN. The loss appears only during high throughput periods. They require evidence of whether drops are due to security rule denies, route misconfiguration, or path MTU issues. Which combination of OCI features is the most appropriate to implement?

You need to provide private connectivity from an OCI VCN to multiple OCI services and to a third-party SaaS reachable only via public IPs, while ensuring that instances never get public IPs and that egress is tightly controlled and observable. You must also support future insertion of a third-party firewall for selective inspection. Which architecture best meets these goals?