This PCSE practice question tests your understanding of configuring 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 THREE of the following are required to enable VPC Flow Logs for a subnet? (Choose THREE.)
A subnet in the VPC
Flow logs are per-subnet.
Setting the subnet's flow logs configuration to ON
This enables flow logging for that subnet.
A VPC network
Flow logs are enabled at the subnet level within a VPC.
A sample rate
Why wrong: Sample rate is optional; default is 0.5.
An aggregation interval
Why wrong: Aggregation interval is optional.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
A subnet in the VPC
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
A subnet in the VPC
Why this is correct
Flow logs are per-subnet.
Related concept
Read the scenario before looking for a memorised answer.
Setting the subnet's flow logs configuration to ON
Why this is correct
This enables flow logging for that subnet.
Related concept
Read the scenario before looking for a memorised answer.
A VPC network
Why this is correct
Flow logs are enabled at the subnet level within a VPC.
Related concept
Read the scenario before looking for a memorised answer.
A sample rate
Why it's wrong here
Sample rate is optional; default is 0.5.
An aggregation interval
Why it's wrong here
Aggregation interval is optional.
Common exam traps
Google Cloud often tests the distinction between required components (subnet, VPC, flow logs ON) and optional tuning parameters (sample rate, aggregation interval), leading candidates to mistakenly select the latter as mandatory.
Detailed technical explanation
VPC Flow Logs use a network monitoring agent in the hypervisor to capture packet metadata (e.g., source/destination IP, ports, protocol) for all traffic accepted or denied by security groups and network ACLs. The logs are published to CloudWatch Logs or S3, and the subnet acts as the scope for log collection. In real-world scenarios, enabling flow logs on a subnet without specifying a sample rate or aggregation interval defaults to capturing 100% of flows with a 10-minute aggregation window.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Configuring network security — This question tests Configuring network security — Read the scenario before looking for a memorised answer..
The correct answer is: A subnet in the VPC — 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
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.
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