PCNE Configuring Network Services Practice Question
A company uses Cloud CDN with an external HTTP(S) load balancer. They have two origin server groups: a primary in us-central1 and a backup in europe-west1. They want traffic directed to the primary unless it is unhealthy, in which case traffic should fail over to the backup. Which configuration is required?
⚠ Common exam trap
Test-takers frequently confuse Cloud CDN's origin settings with backend service failover policies, assuming CDN itself handles failover, when in fact failover is a property of the backend service used by the external HTTP(S) load balancer.
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
✓
Create a backend service with two backends (primary and failover) and a failover policy that marks the primary as failover when unhealthy.
Cloud CDN with an external HTTP(S) load balancer uses a backend service that can contain multiple backends (e.g., instance groups or NEGs) with a failover policy. When the primary backend is marked as unhealthy by the health check, the load balancer automatically routes traffic to the failover backend. This configuration meets the requirement without manual intervention.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create a Cloud CDN with two origins and enable failover in the CDN settings.
Why it's wrong here
Cloud CDN itself does not have failover; it relies on the load balancer.
- ✗
Use a TCP/UDP network load balancer with two target pools.
Why it's wrong here
Network load balancer does not support HTTP health checking or failover policies.
- ✗
Configure a weighted round-robin with primary weight 100 and backup weight 0, and change weights manually.
Why it's wrong here
This is not automated failover and not recommended.
- ✓
Create a backend service with two backends (primary and failover) and a failover policy that marks the primary as failover when unhealthy.
Why this is correct
This is the correct architecture for failover across origins.
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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.