PCNE Implementing VPC Instances Practice Question
A company wants to deploy a network appliance (e.g., firewall) on a Compute Engine instance that requires inspecting traffic between two VPCs. The instance must have interfaces in both VPCs. Which three configurations are required? (Choose three.)
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Attach at least two network interfaces (NIC0 and NIC1)
For a multi-NIC network appliance, you need at least two network interfaces (NIC0, NIC1) attached to different VPCs. Each interface must be in a different subnet. Also, IP forwarding must be enabled on the instance to allow it to forward traffic between interfaces.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Assign an external IP to each interface
Why it's wrong here
External IPs are not required; the appliance can use internal IPs.
- ✓
Attach at least two network interfaces (NIC0 and NIC1)
Why this is correct
Required to connect to two different VPCs.
- ✗
Use the same subnet for both interfaces
Why it's wrong here
Each interface must be in a different subnet (and typically different VPC) to route between VPCs.
- ✓
Configure static routes in both VPCs pointing to the appliance's IP
Why this is correct
Required for traffic in each VPC to be directed to the appliance for inspection.
- ✓
Enable IP forwarding on the instance
Why this is correct
Required for the instance to forward traffic between its interfaces.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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