The answer is that the VPC endpoint does not have 'Private DNS names enabled'. This is the most likely cause of the VPC endpoint private DNS names enabled failure because, even when an endpoint is in the 'available' state and the service has a PrivateDnsName, the Route 53 private hosted zone will only resolve that name if the endpoint explicitly enables this feature. Without it, instances in the VPC cannot resolve the private DNS name 'example.com', as the DNS resolution is not automatically delegated to the endpoint’s hosted zone. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of VPC endpoint DNS behavior and the distinction between endpoint availability and DNS resolution readiness. A common trap is assuming an 'available' endpoint automatically resolves private names, but the key is that 'Private DNS names enabled' is a separate toggle that must be set during or after endpoint creation. Memory tip: think of it as a "DNS switch" — the endpoint is ready, but the DNS resolution is off until you flip that switch.
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A network engineer created a VPC endpoint for the service shown in the exhibit. The endpoint is in the 'available' state, but instances in the VPC cannot resolve the private DNS name 'example.com'. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The endpoint does not have 'Private DNS names enabled'
The private DNS name is only resolved via Route 53 private hosted zone if 'Private DNS names enabled' is set. The exhibit shows the service has a PrivateDnsName, but the endpoint must have 'Private DNS names enabled' for resolution to work.
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.
✗
The VPC does not have a Route 53 private hosted zone for example.com
Why it's wrong here
The endpoint can automatically manage private DNS if enabled; a private hosted zone is not required separately.
✗
The VPC does not have an internet gateway
Why it's wrong here
Internet gateway is not needed for endpoint private DNS resolution.
✓
The endpoint does not have 'Private DNS names enabled'
Why this is correct
Without enabling this option, the private DNS name is not resolved.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The security group for the endpoint is blocking DNS traffic
Why it's wrong here
Security groups do not affect DNS resolution; they affect traffic to the endpoint.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Got this wrong? Here's your next step.
Identify which ANS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The endpoint does not have 'Private DNS names enabled' — The private DNS name is only resolved via Route 53 private hosted zone if 'Private DNS names enabled' is set. The exhibit shows the service has a PrivateDnsName, but the endpoint must have 'Private DNS names enabled' for resolution to work.
What should I do if I get this ANS-C01 question wrong?
Identify which ANS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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