The correct answer is a NAT gateway deployed in a public subnet with a route from the private subnet, or a NAT instance configured similarly. Both methods allow instances in a private subnet to initiate outbound internet traffic while preventing unsolicited inbound connections, because the NAT device translates the private source IP to its own public IP. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this concept tests your understanding of how to architect secure outbound connectivity without assigning public IPs to private instances. A common trap is confusing an internet gateway, which requires public IPs on instances, with a NAT gateway, which does not. Remember that VPC endpoints only work for AWS services, and a VPN provides private connectivity, not direct internet access. A useful memory tip: NAT stands for “Not Allowing Traffic In”—it only forwards outbound replies.
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.
Which TWO of the following are valid methods to provide outbound internet access to instances in a private subnet?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Deploy a NAT instance in a public subnet and configure routing
Option A is correct because NATgateway provides outbound internet access. Option B is correct because NAT instance can also provide this functionality. Option C is wrong because internet gateway is attached to the VPC but requires instances to have public IPs, which is not suitable for private subnets. Option D is wrong because VPC endpoints are for accessing AWS services only. Option E is wrong because VPN does not provide direct internet access.
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.
✗
Use a VPC endpoint for internet access
Why it's wrong here
VPC endpoints provide private access to AWS services, not general internet.
✗
Attach an internet gateway directly to the private subnet
Why it's wrong here
Internet gateway requires instances to have public IPs; private subnets do not have direct internet gateway attachment.
✓
Deploy a NAT instance in a public subnet and configure routing
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 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
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: Deploy a NAT instance in a public subnet and configure routing — Option A is correct because NAT gateway provides outbound internet access. Option B is correct because NAT instance can also provide this functionality. Option C is wrong because internet gateway is attached to the VPC but requires instances to have public IPs, which is not suitable for private subnets. Option D is wrong because VPC endpoints are for accessing AWS services only. Option E is wrong because VPN does not provide direct internet access.
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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