PCNE Implementing VPC Instances Practice Question
An engineer needs to configure a Compute Engine instance as a network appliance that routes traffic between two subnets within the same VPC. The instance must handle traffic for both subnets. Which TWO actions are required? (Choose TWO.)
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
✓
Enable IP forwarding on the instance
To act as a router between subnets, the instance needs two network interfaces, each attached to a different subnet, and IP forwarding must be enabled so the kernel can forward packets 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.
- ✗
Set the MTU to 1500 on both interfaces
Why it's wrong here
GCP's default MTU is 1460, but 1500 is not required for routing.
- ✗
Create a route with a next-hop of the instance's internal IP
Why it's wrong here
Routes are needed to direct traffic to the appliance, but the question asks for actions on the instance itself.
- ✓
Enable IP forwarding on the instance
Why this is correct
IP forwarding allows the instance to forward packets between interfaces.
- ✓
Attach two network interfaces to the instance, one in each subnet
Why this is correct
Multiple NICs allow the instance to be on multiple subnets.
- ✗
Assign external IPs to both interfaces
Why it's wrong here
External IPs are not required for internal routing.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCNE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCNE exam.