The answer is detecting and alerting on malware spreading between VMs in the same VPC and inspecting traffic traversing Cloud VPN for threats in hybrid networks. Cloud IDS, powered by Palo Alto Networks, performs deep packet inspection against all VPC traffic, including east-west flows between instances, which allows it to catch malware propagation that traditional perimeter defenses miss. Additionally, because Cloud IDS can inspect traffic entering or leaving a VPC through a Cloud VPN tunnel, it provides critical visibility into encrypted hybrid traffic between on-premises and Google Cloud, making it a valid use case for threat detection in hybrid networks. On the Google Professional Cloud Network Engineer exam, this question tests your understanding that Cloud IDS is not limited to internet-facing traffic; a common trap is assuming it only inspects traffic at the edge. Remember the memory tip: “East-west and VPN—Cloud IDS inspects the in-between.”
PCNE Implementing network security Practice Question
This PCNE practice question tests your understanding of implementing network security. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 TWO of the following are valid use cases for Cloud IDS? (Choose TWO)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Inspecting traffic between an on-premises network and Google Cloud via Cloud VPN.
Cloud IDS (Intrusion Detection System) inspects traffic for threats like malware and policy violations. Option B is correct because Cloud IDS can inspect traffic traversing Cloud VPN, enabling east-west and hybrid traffic inspection between on-premises and Google Cloud networks, which is a key use case for detecting threats in encrypted VPN tunnels.
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.
✗
Blocking malicious traffic at the network perimeter.
Why it's wrong here
Cloud IDS is detection-only; blocking requires Cloud Armor or firewall rules.
✓
Inspecting traffic between an on-premises network and Google Cloud via Cloud VPN.
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 IDS can block traffic (like a firewall), but Cloud IDS is detection-only and requires separate mitigation tools like Cloud Armor or firewall rules for blocking.
Detailed technical explanation
How to think about this question
Cloud IDS uses a third-party partner (e.g., Palo Alto Networks, Check Point) to perform deep packet inspection (DPI) on mirrored traffic via VPC Flow Logs or Packet Mirroring. It can inspect traffic over Cloud VPN and Cloud Interconnect, but it does not decrypt TLS traffic unless you configure SSL decryption policies. In a real-world scenario, an attacker moving laterally between VMs in the same VPC would be detected by Cloud IDS, as it inspects all internal traffic, not just internet-bound flows.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
Implementing network security — This question tests Implementing network security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Inspecting traffic between an on-premises network and Google Cloud via Cloud VPN. — Cloud IDS (Intrusion Detection System) inspects traffic for threats like malware and policy violations. Option B is correct because Cloud IDS can inspect traffic traversing Cloud VPN, enabling east-west and hybrid traffic inspection between on-premises and Google Cloud networks, which is a key use case for detecting threats in encrypted VPN tunnels.
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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