- A
Create a Transit Gateway and attach both subnets to it.
Why wrong: Transit Gateway is for connecting multiple VPCs or on-premises, not needed within a single VPC.
- B
Place a NAT Gateway in subnet-A and configure route tables accordingly.
Why wrong: NAT Gateway is for internet access, not internal VPC communication.
- C
No additional configuration is required. The instance and database can communicate within the same VPC.
VPC internal routing allows communication between subnets in the same VPC.
- D
Create a VPC Peering connection between the two subnets.
Why wrong: VPC Peering is for connecting different VPCs, not subnets within the same VPC.
Question 882 of 1,705
ANS-C01 Network Design Practice Question
This ANS-C01 practice question tests your understanding of network design. 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 has a VPC with a CIDR block of 10.0.0.0/16. They have two subnets: subnet-A (10.0.1.0/24) and subnet-B (10.0.2.0/24). An EC2 instance in subnet-A needs to communicate with an RDS database in subnet-B. Both subnets are in the same Availability Zone. What is the most efficient way to enable this communication?
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
✓
No additional configuration is required. The instance and database can communicate within the same VPC.
Option C is correct because both the EC2 instance and the RDS database reside within the same VPC (10.0.0.0/16), and subnets within a VPC can communicate with each other by default using the VPC's local route. No additional configuration is needed, as the VPC's main route table or subnet route tables already include a local route for the VPC CIDR, enabling direct communication within the same Availability Zone.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 Transit Gateway and attach both subnets to it.
Why it's wrong here
Transit Gateway is for connecting multiple VPCs or on-premises, not needed within a single VPC.
- ✗
Place a NAT Gateway in subnet-A and configure route tables accordingly.
- ✓
No additional configuration is required. The instance and database can communicate within the same VPC.
Why this is correct
VPC internal routing allows communication between subnets in the same VPC.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a VPC Peering connection between the two subnets.
Why it's wrong here
VPC Peering is for connecting different VPCs, not subnets within the same VPC.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may overthink the scenario and assume that different subnets require additional networking components like a Transit Gateway or VPC Peering, forgetting that subnets within the same VPC inherently have local connectivity via the VPC's route table.
Detailed technical explanation
How to think about this question
Under the hood, the VPC's route tables contain a local route (e.g., 10.0.0.0/16) that is automatically added and cannot be deleted, which directs traffic between any subnets within the VPC. This local route uses the VPC's internal router, which handles all intra-VPC traffic without needing any gateways or additional services. In a real-world scenario, this default behavior ensures low-latency communication between resources in the same VPC, such as an EC2 instance and an RDS database, even across different subnets.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: No additional configuration is required. The instance and database can communicate within the same VPC. — Option C is correct because both the EC2 instance and the RDS database reside within the same VPC (10.0.0.0/16), and subnets within a VPC can communicate with each other by default using the VPC's local route. No additional configuration is needed, as the VPC's main route table or subnet route tables already include a local route for the VPC CIDR, enabling direct communication within the same Availability Zone.
What should I do if I get this ANS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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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