ANS-C01 Question 72
Select 1A company is deploying a web application that consists of two main components: a front-end service that must be accessible to end-users over the public internet, and a back-end API service that should only be accessible from the front-end service within a VPC. Which combination of load balancers should the company use to meet these requirements?
- A
Use an Application Load Balancer (ALB) with a public-facing listener for the front-end service and a Network Load Balancer (NLB) with an internal-facing listener for the back-end service.
- B
Use an Application Load Balancer (ALB) with a public-facing listener for the front-end service and another ALB with an internal-facing listener for the back-end service.
- C
Use a Network Load Balancer (NLB) with a public-facing listener for the front-end service and an ALB with an internal-facing listener for the back-end service.
- D
Use an ALB with a public-facing listener for both the front-end and back-end services, ensuring the back-end service is exposed via a separate path.
- E
Use an NLB with a public-facing listener for both the front-end and back-end services, ensuring traffic is routed internally to the back-end service.
Show answer and explanation
Correct answer: B
Explanation
The appropriate solution for this use case involves leveraging an Application Load Balancer (ALB) for the front-end service with a public-facing listener to handle HTTP/HTTPS traffic from end-users, and another ALB with an internal-facing listener for the back-end API service. This setup provides advanced routing capabilities and ensures secure, internal-only access to the back-end service while meeting the connectivity patterns required for this scenario.
- A. Incorrect.
This option uses an ALB for the front-end and an NLB for the back-end. While this is technically possible, it introduces unnecessary complexity because NLBs are not required in this specific use case. ALBs are better suited for HTTP/HTTPS traffic and path-based routing.
- B. Correct.
This is the correct approach. Using an ALB with a public-facing listener for the front-end service ensures seamless public internet access with advanced HTTP/HTTPS features. An internal ALB for the back-end service ensures secure communication between the front-end and back-end, leveraging path-based or host-based routing as needed.
- C. Incorrect.
Using an NLB for the front-end service is not recommended for HTTP/HTTPS workloads, as it lacks advanced routing features. While the back-end service could use an ALB, this pairing doesn't align well with the use case.
- D. Incorrect.
This option uses a single ALB for both the front-end and back-end services. While possible, it violates the requirement to isolate the back-end service and restrict access to only the front-end service.
- E. Incorrect.
This option uses an NLB for both services, which is not ideal. NLBs are not well-suited for HTTP/HTTPS workloads due to the lack of advanced routing features and content-based routing.