- A
Create a bastion host in the public subnet and configure the web server to use it as a proxy.
Why wrong: A bastion host is for administrative access, not for internet connectivity for patching.
- B
Create a VPC endpoint for Amazon S3.
Why wrong: This only allows access to S3, not general internet.
- C
Create a NAT Gateway in the public subnet.
NAT Gateway enables outbound internet access for instances in private subnets.
- D
Attach an Internet Gateway to the VPC and add a route to the Internet Gateway in the private subnet's route table.
Why wrong: Private subnets should not have direct routes to an Internet Gateway.
- E
Add a route in the private subnet's route table that points 0.0.0.0/0 to the NAT Gateway.
This routes outbound internet traffic from the private subnet through the NAT Gateway.
Quick Answer
The correct answer is to add a route in the private subnet’s route table that points 0.0.0.0/0 to a NAT Gateway. This works because a NAT Gateway, deployed in a public subnet with an Elastic IP, allows instances in private subnets to initiate outbound traffic to the internet for tasks like downloading patches, while blocking any unsolicited inbound connections that could expose the database. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of VPC networking and the distinction between NAT Gateways and Internet Gateways—a common trap is confusing the two, but remember that only public subnets use an Internet Gateway directly. The exam often pairs this with a distractor like a VPC endpoint for S3, which is for private AWS service access, not general internet. A helpful memory tip: NAT Gateway = outbound only, private subnet; Internet Gateway = bidirectional, public subnet.
SCS-C02 Infrastructure Security Practice Question
This SCS-C02 practice question tests your understanding of infrastructure security. 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 Security Engineer is configuring a VPC with a public subnet for a web server and a private subnet for a database. The web server needs to download patches from the internet. Which TWO actions should the Engineer take to allow the web server internet access without exposing the database to the internet?
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
Create a NAT Gateway in the public subnet.
Option A (NAT Gateway) and Option C (route table update) are correct because a NAT Gateway in the public subnet allows instances in private subnets to initiate outbound traffic to the internet, and updating the private subnet route table directs internet-bound traffic to the NAT Gateway. Option B is wrong because an Internet Gateway is used for public subnets, not private. Option D is wrong because a VPC endpoint for S3 is for accessing S3 privately, not for general internet access. Option E is wrong because a bastion host is for SSH access, not for 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.
- ✗
Create a bastion host in the public subnet and configure the web server to use it as a proxy.
Why it's wrong here
A bastion host is for administrative access, not for internet connectivity for patching.
- ✗
Create a VPC endpoint for Amazon S3.
Why it's wrong here
This only allows access to S3, not general internet.
- ✓
Create a NAT Gateway in the public subnet.
- ✗
Attach an Internet Gateway to the VPC and add a route to the Internet Gateway in the private subnet's route table.
Why it's wrong here
Private subnets should not have direct routes to an Internet Gateway.
- ✓
Add a route in the private subnet's route table that points 0.0.0.0/0 to the NAT Gateway.
Common exam traps
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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 SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Questions learners often ask
What does this SCS-C02 question test?
Infrastructure Security — This question tests Infrastructure Security — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Create a NAT Gateway in the public subnet. — Option A (NAT Gateway) and Option C (route table update) are correct because a NAT Gateway in the public subnet allows instances in private subnets to initiate outbound traffic to the internet, and updating the private subnet route table directs internet-bound traffic to the NAT Gateway. Option B is wrong because an Internet Gateway is used for public subnets, not private. Option D is wrong because a VPC endpoint for S3 is for accessing S3 privately, not for general internet access. Option E is wrong because a bastion host is for SSH access, not for internet access.
What should I do if I get this SCS-C02 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 SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
2 more ways this is tested on SCS-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A security engineer is configuring a VPC with public and private subnets. The engineer needs to allow instances in the private subnet to download software updates from the internet. Which component should be added to the VPC?
easy- A.VPN connection to on-premises.
- B.VPC endpoint for Amazon S3.
- C.Bastion host in a public subnet.
- ✓ D.NAT gateway in a public subnet.
Why D: Option A is correct because a NAT gateway allows outbound internet access from private subnets. Option B is wrong because a bastion host is for SSH/RDP access, not internet access. Option C is wrong because a VPC endpoint is for private access to AWS services. Option D is wrong because a VPN connection is for hybrid networking.
Variation 2. A security engineer is configuring a VPC with a public subnet for web servers and a private subnet for databases. The web servers need to download patches from the internet. Which TWO components are required to allow the web servers to access the internet while keeping the database servers isolated?
easy- ✓ A.Internet gateway attached to the VPC.
- B.VPC endpoint for Amazon S3.
- C.Transit gateway between the public and private subnets.
- ✓ D.NAT gateway in the public subnet.
- E.Virtual private gateway attached to the VPC.
Why A: Option A is correct because an internet gateway is needed for the public subnet to reach the internet. Option C is correct because a NAT gateway in the public subnet allows the private subnet instances to initiate outbound traffic to the internet (for patches) while preventing inbound traffic from the internet. Option B is wrong because a virtual private gateway is for VPN connections. Option D is wrong because a transit gateway is for connecting multiple VPCs. Option E is wrong because a VPC endpoint is for accessing AWS services privately, not internet.
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Last reviewed: Jun 20, 2026
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