ANS-C01 Network Management and Operations Practice Question
A company has a VPC with public and private subnets. The private subnets have a route to a NAT gateway. The network team wants to monitor DNS queries from EC2 instances in private subnets to a custom DNS resolver on-premises over a VPN. Which TWO services can capture this traffic?
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
✓
VPC Flow Logs
VPC Flow Logs capture IP traffic at the network interface level, including DNS queries (port 53) to any destination, such as a custom on-premises resolver over VPN. AWS Network Firewall can inspect and log DNS traffic that passes through it, including queries to custom resolvers. Option A (Route 53 Resolver query logs) is incorrect because it only logs queries made to Amazon Route 53 Resolver, not to custom on-premises resolvers. Option B (CloudWatch) is incorrect because CloudWatch does not directly capture network traffic; it can aggregate logs but cannot capture raw DNS packets. Option E (CloudTrail) is incorrect because it logs API calls to AWS services, not network traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Amazon Route 53 Resolver query logs
Why it's wrong here
Resolver query logs capture queries to Route 53, not custom on-premises resolvers.
- ✗
Amazon CloudWatch
Why it's wrong here
CloudWatch is for monitoring metrics and logs, not capturing traffic directly.
- ✓
VPC Flow Logs
Why this is correct
Flow logs capture all IP traffic, including DNS queries.
- ✓
AWS Network Firewall
Why this is correct
Network Firewall can log traffic including DNS based on stateful rules.
- ✗
AWS CloudTrail
Why it's wrong here
CloudTrail records API calls, not network traffic.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services 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 ANS-C01 exam.