- A
Use an Internet Gateway to route traffic between subnets
Why wrong: Incorrect; Internet Gateways expose traffic to the internet, which is not private.
- B
Use VPC Peering between the subnets
Why wrong: Incorrect; VPC Peering connects different VPCs, not subnets within the same VPC.
- C
Use a NAT Gateway in each subnet for inter-subnet communication
Why wrong: Incorrect; NAT Gateways are for outbound traffic to the internet, not for private communication.
- D
Use route tables and security groups to allow traffic within the VPC
Correct; local routes already enable communication within a VPC; security groups and NACLs provide security.
Question 130 of 1,705
Routing Traffic Within a VPC Without Internet Transit
This ANS-C01 practice question tests your understanding of network implementation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 is deploying a multi-tier application on AWS and needs to ensure that traffic between the web tier and the application tier does not traverse the internet. Both tiers are deployed in the same VPC but in different subnets. What is the MOST secure way to meet this requirement?
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
✓
Use route tables and security groups to allow traffic within the VPC
The most secure way to ensure that traffic between the web tier and the application tier does not traverse the internet is to use route tables and security groups to allow traffic within the VPC. Both tiers are in the same VPC but in different subnets, so traffic stays within the VPC by default if routing is configured correctly. Route tables direct traffic between subnets, and security groups act as virtual firewalls to control inbound and outbound traffic. Option D is correct. Option A is wrong because an Internet Gateway is used for internet access, not for routing within a VPC. Option B is wrong because VPC Peering connects different VPCs, not subnets within the same VPC. Option C is wrong because a NAT Gateway is for outbound internet access from private subnets, not for inter-subnet communication.
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 an Internet Gateway to route traffic between subnets
Why it's wrong here
Incorrect; Internet Gateways expose traffic to the internet, which is not private.
- ✗
Use VPC Peering between the subnets
Why it's wrong here
Incorrect; VPC Peering connects different VPCs, not subnets within the same VPC.
- ✗
Use a NAT Gateway in each subnet for inter-subnet communication
Why it's wrong here
Incorrect; NAT Gateways are for outbound traffic to the internet, not for private communication.
- ✓
Use route tables and security groups to allow traffic within the VPC
Why this is correct
Correct; local routes already enable communication within a VPC; security groups and NACLs provide security.
Related concept
CIDR notation defines the prefix length.
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.
Visual reference
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.
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
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: Use route tables and security groups to allow traffic within the VPC — The most secure way to ensure that traffic between the web tier and the application tier does not traverse the internet is to use route tables and security groups to allow traffic within the VPC. Both tiers are in the same VPC but in different subnets, so traffic stays within the VPC by default if routing is configured correctly. Route tables direct traffic between subnets, and security groups act as virtual firewalls to control inbound and outbound traffic. Option D is correct. Option A is wrong because an Internet Gateway is used for internet access, not for routing within a VPC. Option B is wrong because VPC Peering connects different VPCs, not subnets within the same VPC. Option C is wrong because a NAT Gateway is for outbound internet access from private subnets, not for inter-subnet communication.
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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Last reviewed: Jun 20, 2026
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.
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