AWS Certified Solutions Architect Professional · Free Practice Question Hard
Question 32
A company is running a two-tier web-based application in an on-premises data center. The application layer consists of a single server running a stateless application. The application connects to a PostgreSQL database running on a separate server. A Solutions Architect is planning a migration to AWS. The company requires that the application and database layer must be highly available across three availability zones.
Which solution will meet the company’s requirements?
-
A
Create an Auto Scaling group of Amazon EC2 instances across three availability zones behind an Application Load Balancer. Create an Amazon Aurora PostgreSQL database in one AZ and add Aurora Replicas in two more AZs.
-
B
Create an Auto Scaling group of Amazon EC2 instances across three availability zones behind a Network Load Balancer. Create an Amazon Aurora PostgreSQL database in one AZ with storage auto scaling enabled.
-
C
Create an Auto Scaling group of Amazon EC2 instances across three availability zones behind an Application Load Balancer. Create an Amazon Aurora Global database.
-
D
Create an Auto Scaling group of Amazon EC2 instances across three availability zones behind a Network Load Balancer. Create an Amazon RDS Multi-AZ PostgreSQL database across two AZs and add a Read Replica in a third AZ.
Reveal correct answer
Correct answer: A
Explanation
All answers include an ASG with Auto Scaling across three AZs. An Application Load Balancer is better suited to this particular use case but a Network Load Balancer could also be used. The key to answering correctly is to choose a storage solution that meets the requirement of high availability across three Availability Zones (AZs).
With Amazon Aurora you can have one writer instance and up to 15 Aurora Replicas. Aurora Replicas are read-only but are automatically promoted to be writer instances in the event of a failure. Therefore, for this solution we can have a single Aurora writer instance and two Aurora Replicas, each in separate AZs.
CORRECT: "Create an Auto Scaling group of Amazon EC2 instances across three availability zones behind an Application Load Balancer. Create an Amazon Aurora PostgreSQL database in one AZ and add Aurora Replicas in two more AZs" is the correct answer.
INCORRECT: "Create an Auto Scaling group of Amazon EC2 instances across three availability zones behind an Application Load Balancer. Create an Amazon Aurora Global database" is incorrect. Global database is used for cross-Region databases which is not required in this scenario.
INCORRECT: "Create an Auto Scaling group of Amazon EC2 instances across three availability zones behind a Network Load Balancer. Create an Amazon Aurora PostgreSQL database in one AZ with storage auto scaling enabled" is incorrect. Storage auto scaling is enabled for all Aurora databases and does not provide high availability for the database, it provides scaling for the storage.
References:
https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Replication.html
Save time with our AWS cheat sheets:
Discussion
Think the marked answer is wrong, or have a better explanation? Share it below — comments appear after review.
