- A
Set up a VPC peering connection between the subnets
Why wrong: VPC peering connects different VPCs, not subnets within the same VPC.
- B
Use a Transit Gateway to route traffic through the appliance
Why wrong: Transit Gateway is used for inter-VPC connectivity, not intra-subnet traffic inspection.
- C
Deploy AWS Network Firewall in the subnet
Why wrong: AWS Network Firewall inspects traffic crossing VPC boundaries, not within a subnet.
- D
Create a Gateway Load Balancer and configure the appliance as a target
GWLB can be used to inspect all traffic between instances in the same subnet via a Gateway Load Balancer Endpoint.
Question 418 of 1,705
ANS-C01 Gateway Load Balancer (GWLB) 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. A key principle to apply: gateway Load Balancer (GWLB). 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 an application across multiple Availability Zones in a single AWS Region. The application requires that all traffic between EC2 instances in the same subnet be inspected by a network appliance. Which configuration should be used 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
✓
Create a Gateway Load Balancer and configure the appliance as a target
Option D is correct because a Gateway Load Balancer (GWLB) can inspect intra-subnet traffic between EC2 instances in the same subnet. Traffic between instances in the same subnet is Layer 2 and does not traverse route tables, so traditional routing methods cannot intercept it. GWLB uses Geneve encapsulation to transparently redirect traffic at the hypervisor level to the appliance targets without modifying the route table. The appliance must be configured to handle this encapsulation. Other options do not support inspection of same-subnet traffic.
Key principle: Gateway Load Balancer (GWLB)
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Set up a VPC peering connection between the subnets
Why it's wrong here
VPC peering connects different VPCs, not subnets within the same VPC.
- ✗
Use a Transit Gateway to route traffic through the appliance
Why it's wrong here
Transit Gateway is used for inter-VPC connectivity, not intra-subnet traffic inspection.
- ✗
Deploy AWS Network Firewall in the subnet
Why it's wrong here
AWS Network Firewall inspects traffic crossing VPC boundaries, not within a subnet.
- ✓
Create a Gateway Load Balancer and configure the appliance as a target
Why this is correct
GWLB can be used to inspect all traffic between instances in the same subnet via a Gateway Load Balancer Endpoint.
Related concept
Gateway Load Balancer (GWLB)
Common exam traps
Common exam trap: answer the scenario, not the keyword
The ANS-C01 exam often tests the misconception that intra-subnet traffic can be intercepted by a firewall or routing construct, but in AWS, traffic between instances in the same subnet is Layer 2 and never hits a route table, so only a Gateway Load Balancer (or an inline appliance with proxy ARP) can inspect it.
Detailed technical explanation
How to think about this question
Gateway Load Balancer uses the Geneve protocol (port 6081) to encapsulate traffic between the GWLB endpoint and the appliance targets, allowing the appliance to inspect packets and return them to the GWLB for final delivery. This enables symmetric hairpinning of intra-subnet traffic without requiring changes to the instances' source/destination check settings. In a real-world scenario, this is commonly used for East-West inspection of micro-segmented workloads where compliance mandates that all traffic between application tiers must pass through a next-generation firewall.
KKey Concepts to Remember
- Gateway Load Balancer (GWLB)
- Intra-subnet traffic
- Geneve encapsulation
- Proxy ARP
TExam Day Tips
- 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
Gateway Load Balancer (GWLB)
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Visual reference
What to study next
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Implementation — This question tests Network Implementation — Gateway Load Balancer (GWLB).
What is the correct answer to this question?
The correct answer is: Create a Gateway Load Balancer and configure the appliance as a target — Option D is correct because a Gateway Load Balancer (GWLB) can inspect intra-subnet traffic between EC2 instances in the same subnet. Traffic between instances in the same subnet is Layer 2 and does not traverse route tables, so traditional routing methods cannot intercept it. GWLB uses Geneve encapsulation to transparently redirect traffic at the hypervisor level to the appliance targets without modifying the route table. The appliance must be configured to handle this encapsulation. Other options do not support inspection of same-subnet traffic.
What should I do if I get this ANS-C01 question wrong?
Review gateway Load Balancer (GWLB), then practise related ANS-C01 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Gateway Load Balancer (GWLB)
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Last reviewed: Jul 4, 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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