ANS-C01 Security Groups Practice Question
A company is designing a network security architecture for a multi-tier application. They want to ensure that the web tier can communicate with the application tier only on specific ports, and the application tier can communicate with the database tier only on specific ports. Which TWO configurations should be implemented?
⚠ Common exam trap
Candidates often mistakenly choose transit gateway or VPC peering solutions for intra-VPC traffic filtering, but these are designed for inter-VPC connectivity, not for tier segmentation within a single VPC.
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 network ACLs to provide a secondary layer of stateless filtering at the subnet level.
The correct answers are C and E. Security groups (E) are stateful and can reference other security groups as a source, allowing traffic between tiers only on required ports. Network ACLs (C) are stateless and provide a secondary layer of filtering at the subnet level. Option A is wrong because a transit gateway is used to connect multiple VPCs, not for filtering within a VPC. Option B is wrong because VPC peering connects VPCs, and security groups cannot be applied to a peering connection. Option D is wrong because a single security group cannot differentiate traffic between tiers; each tier needs its own security group.
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 transit gateway with network ACLs to filter traffic between tiers.
Why it's wrong here
Transit gateway is for connecting multiple VPCs, not for security filtering within a VPC.
- ✗
Use VPC peering to connect the tiers and apply security groups on the peering connection.
Why it's wrong here
VPC peering is for connecting VPCs, not for filtering traffic within a VPC.
- ✓
Use network ACLs to provide a secondary layer of stateless filtering at the subnet level.
Why this is correct
Network ACLs can be used to further restrict traffic between subnets.
- ✗
Use a single security group for all tiers and define rules based on CIDR blocks.
Why it's wrong here
A single security group cannot differentiate between tiers effectively.
- ✓
Use security groups for each tier and allow traffic only from the source security group on the required ports.
Why this is correct
Security groups allow you to reference other security groups as sources, enabling precise control.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.