The answer is Cloud Armor security policies to protect against attacks. This is correct because when configuring a global external HTTP(S) load balancer with Cloud CDN and an origin backend that requires authentication, you must also set up an origin access identity—typically a Google-managed service account—to authenticate requests from Cloud CDN to the origin, ensuring only authorized CDN edge caches fetch content. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of securing custom origins behind Cloud CDN, where a common trap is forgetting that the origin access identity is separate from Cloud Armor policies; Cloud Armor protects the load balancer itself from DDoS and application attacks, not the authentication between CDN and origin. A useful memory tip: think of Cloud Armor as the front door guard, while the origin access identity is the key that lets the CDN courier through the back door.
PCNE Configuring network services Practice Question
This PCNE practice question tests your understanding of configuring network services. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE components are necessary to configure a global external HTTP(S) load balancer with Cloud CDN and an origin backend that requires authentication? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
An origin access identity (e.g., service account) to authenticate to the backend.
Option C is correct because when the origin backend (e.g., an external HTTP server or a custom origin) requires authentication, you must configure an origin access identity, typically a Google-managed service account, to authenticate requests from Cloud CDN to the origin. This ensures that only authorized CDN edge caches can fetch content from the backend, preventing direct unauthenticated access.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
An origin access identity (e.g., service account) to authenticate to the backend.
Why this is correct
To access authenticated backends, you need a service account or signed URLs.
Related concept
Read the scenario before looking for a memorised answer.
✓
A backend bucket configured with Cloud CDN enabled.
Why this is correct
Backend bucket is used for CDN.
Related concept
Read the scenario before looking for a memorised answer.
✓
Cloud Armor security policies to protect against attacks.
Why this is correct
Cloud Armor is commonly used with global L7 LBs to provide security.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that a regional load balancer can be used with Cloud CDN, but Cloud CDN requires a global external HTTP(S) load balancer to leverage the global anycast IP and edge cache infrastructure.
Detailed technical explanation
How to think about this question
The origin access identity is a service account that Cloud CDN uses to authenticate to the backend via signed headers (e.g., `x-goog-*` headers) or mutual TLS. This mechanism is critical when the backend is a custom origin (not a Google Cloud Storage bucket) that enforces authentication, such as an on-premises server or a third-party API. Without this identity, the CDN would fail to fetch content, leading to 401 or 403 errors.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Configuring network services — This question tests Configuring network services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: An origin access identity (e.g., service account) to authenticate to the backend. — Option C is correct because when the origin backend (e.g., an external HTTP server or a custom origin) requires authentication, you must configure an origin access identity, typically a Google-managed service account, to authenticate requests from Cloud CDN to the origin. This ensures that only authorized CDN edge caches can fetch content from the backend, preventing direct unauthenticated access.
What should I do if I get this PCNE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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