PCNE Practice Question: Managing, Monitoring, and Optimising Network Operations
An engineer notices that VPC Flow Logs are enabling on a subnet but only a fraction of traffic is logged. What is the most likely cause?
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
✓
Default sampling rate of 50% is applied
VPC Flow Logs use sampling by default (50%) to reduce cost and volume. This means only half of the flows are logged.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The log export filter is too restrictive
Why it's wrong here
Log export filters apply to the destination, not sampling.
- ✓
Default sampling rate of 50% is applied
Why this is correct
Default sampling rate is 50%, so half the flows are logged.
- ✗
The subnet has an insufficient sampling rate set to 0.5
Why it's wrong here
Sampling rate is 0.5 by default, meaning 50% of flows.
- ✗
Flow Logs only log TCP traffic
Why it's wrong here
Flow Logs log TCP, UDP, ICMP, etc.
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JA
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.