The answer is a VM with a network interface in the subnet, the subnet itself with flow logs enabled, and the VM’s service account with the compute.instances.get permission. VPC Flow Logs capture network traffic metadata at the subnet level, so enabling flow logs on the subnet is the primary configuration step that activates logging for all VM instances within that subnet. The VM’s service account must have the compute.instances.get permission to allow the flow log agent to retrieve instance metadata required for log entries, and a VM with a network interface in the subnet is necessary because flow logs are generated per network interface—without a VM in the subnet, there is no traffic to log. On the Google Professional Cloud Security Engineer exam, this tests your understanding that flow logs are subnet-scoped, not instance-scoped, and a common trap is forgetting the service account permission or assuming the VM itself is the configuration target. Memory tip: think “Subnet, Service Account, and a VM inside it” as the three pillars of flow log setup.
PCSE Configuring network security Practice Question
This PCSE practice question tests your understanding of configuring network security. 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 required to configure VPC Flow Logs for a Compute Engine instance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable VPC Flow Logs on the subnet
VPC Flow Logs capture network traffic metadata at the subnet level. Enabling flow logs on the subnet (A) is the primary configuration step that activates logging for all VM instances within that subnet. The VM's service account must have the compute.instances.get permission (B) to allow the flow log agent to retrieve instance metadata required for log entries. A VM with a network interface in the subnet (D) is necessary because flow logs are generated per network interface; without a VM in the subnet, there is no traffic to log.
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.
✓
Enable VPC Flow Logs on the subnet
Why this is correct
Flow logs are enabled per subnet.
Related concept
Read the scenario before looking for a memorised answer.
✓
The VM's service account must have the compute.instances.get permission
Why this is correct
Required to retrieve logs for the instance.
Related concept
Read the scenario before looking for a memorised answer.
✗
A log sink to export logs to BigQuery
Why it's wrong here
Optional, not required for enabling flow logs.
✓
A VM with a network interface in the subnet
Why this is correct
Traffic to/from that interface is logged.
Related concept
Read the scenario before looking for a memorised answer.
✗
A metadata server to store logs
Why it's wrong here
Logs are stored in Cloud Logging, not metadata server.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that a log sink or external export destination is a required component for VPC Flow Logs, when in fact the logs are natively stored in Cloud Logging and exporting is optional.
Detailed technical explanation
How to think about this question
VPC Flow Logs use sampled packet headers (not full payloads) to generate log entries that include source/destination IP, ports, protocol, and packet count. The logs are collected by the Compute Engine hypervisor and sent to Cloud Logging via a background process that requires the VM's service account to have the compute.instances.get permission to associate logs with the correct instance. In a real-world scenario, enabling flow logs on a subnet can help diagnose asymmetric routing or identify unexpected traffic patterns, but the logs themselves are stored in Cloud Logging and can be exported to BigQuery for long-term analysis.
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.
Configuring network security — This question tests Configuring network security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable VPC Flow Logs on the subnet — VPC Flow Logs capture network traffic metadata at the subnet level. Enabling flow logs on the subnet (A) is the primary configuration step that activates logging for all VM instances within that subnet. The VM's service account must have the compute.instances.get permission (B) to allow the flow log agent to retrieve instance metadata required for log entries. A VM with a network interface in the subnet (D) is necessary because flow logs are generated per network interface; without a VM in the subnet, there is no traffic to log.
What should I do if I get this PCSE 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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which THREE of the following are required to enable VPC Flow Logs for a subnet? (Choose THREE.)
hard
✓ A.A subnet in the VPC
✓ B.Setting the subnet's flow logs configuration to ON
✓ C.A VPC network
D.A sample rate
E.An aggregation interval
Why A: A subnet in the VPC is required because VPC Flow Logs capture IP traffic metadata at the subnet level. Without a subnet, there is no network segment to monitor, as flow logs are associated with a specific subnet within a VPC.
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This PCSE 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 PCSE exam.
Question Discussion
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