This ANS-C01 practice question tests your understanding of network design. 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 large e-commerce company is designing a network for a new microservices architecture. They have hundreds of microservices running on Amazon ECS with Fargate launch type. The services need to communicate with each other and with external APIs. The company wants to minimize network latency and maximize security. They also need to ensure that traffic between services does not leave the VPC. The network engineer is considering using AWS PrivateLink to allow services to communicate via VPC endpoints. However, they are concerned about the cost of creating an endpoint for each service. Which design should the network engineer recommend?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use AWS App Mesh to enable service-to-service communication within the VPC
AWS App Mesh provides a service mesh that enables secure, low-latency communication between microservices within the same VPC using Envoy sidecar proxies. It handles service discovery, traffic routing, and encryption (mTLS) without requiring VPC endpoints or public IPs, keeping all traffic within the VPC and minimizing cost. This directly addresses the requirement for hundreds of services to communicate privately and efficiently.
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.
✗
Use a Transit Gateway to connect all services
Why it's wrong here
Transit Gateway is for connecting VPCs, not services within a VPC.
✓
Use AWS App Mesh to enable service-to-service communication within the VPC
Why this is correct
Service Mesh provides secure and low-latency communication without VPC endpoints.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Assign public IP addresses to the Fargate tasks and use security groups
Why it's wrong here
Public IPs may route traffic through the internet and reduce security.
✗
Create a VPC endpoint for each microservice and use PrivateLink
Why it's wrong here
Too many endpoints increase cost and management overhead.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse PrivateLink (designed for external service access) with internal service mesh solutions, assuming VPC endpoints are the only way to keep traffic private, while overlooking App Mesh as a cost-effective, VPC-contained alternative for microservice communication.
Detailed technical explanation
How to think about this question
Under the hood, AWS App Mesh deploys Envoy proxies as sidecar containers alongside each Fargate task, intercepting all traffic via iptables rules. These proxies communicate using the xDS protocol to dynamically update routing tables, enabling features like retries, timeouts, and circuit breaking at Layer 7. In a real-world scenario, this allows a payment microservice to call an inventory service with automatic mTLS encryption and fine-grained traffic splitting for canary deployments, all without leaving the VPC or incurring endpoint costs.
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
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Use AWS App Mesh to enable service-to-service communication within the VPC — AWS App Mesh provides a service mesh that enables secure, low-latency communication between microservices within the same VPC using Envoy sidecar proxies. It handles service discovery, traffic routing, and encryption (mTLS) without requiring VPC endpoints or public IPs, keeping all traffic within the VPC and minimizing cost. This directly addresses the requirement for hundreds of services to communicate privately and efficiently.
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.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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