The correct answer is to set up an IPsec VPN tunnel over the Direct Connect private VIF. This solution works because Direct Connect private VIFs operate at Layer 2 and do not provide any inherent encryption, leaving traffic potentially exposed within the AWS backbone. By layering an IPsec VPN on top of the private VIF, you encrypt the data at the network layer (Layer 3) between the on-premises router and the EC2 instance, ensuring confidentiality without sacrificing the low latency and reliability of the dedicated connection. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of hybrid network security—specifically that Direct Connect alone is not encrypted, and that IPsec is the correct overlay for private VIFs. A common trap is confusing TLS (application layer) or KMS (key management) with network-layer encryption. Memory tip: “Private VIF, no cipher—add IPsec to make it safer.”
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. 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.
A company has a Direct Connect connection with a private VIF to a VPC. The VPC has a subnet that hosts an EC2 instance with a sensitive database. The company wants to add an extra layer of encryption for traffic between the on-premises network and the EC2 instance. Which solution should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set up an IPsec VPN tunnel over the Direct Connect private VIF
Option D is correct because IPsecVPN over Direct Connect provides encryption over the private VIF. Option A is incorrect because Direct Connect traffic is not encrypted by default. Option B is incorrect because TLS is for application-level encryption, not network layer. Option C is incorrect because AWS KMS is for encryption keys, not for network encryption.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 TLS on the EC2 instance
Why it's wrong here
TLS is application-specific; it does not encrypt all network traffic.
✗
Use an SSL certificate on the on-premises router
Why it's wrong here
SSL is for web traffic, not for encrypting all traffic over Direct Connect.
✗
Use AWS Key Management Service (KMS) to encrypt the traffic
Why it's wrong here
KMS is for encryption key management, not for encrypting network traffic.
✓
Set up an IPsec VPN tunnel over the Direct Connect private VIF
Why this is correct
IPsecVPN provides encryption at the network layer over the Direct Connect connection.
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
Network Implementation — This question tests Network Implementation — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Set up an IPsec VPN tunnel over the Direct Connect private VIF — Option D is correct because IPsec VPN over Direct Connect provides encryption over the private VIF. Option A is incorrect because Direct Connect traffic is not encrypted by default. Option B is incorrect because TLS is for application-level encryption, not network layer. Option C is incorrect because AWS KMS is for encryption keys, not for network encryption.
What should I do if I get this ANS-C01 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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