AWS Certified Solutions Architect – Associate (SAA-C02) — Question 367

A company hosts its application using Amazon Elastic Container Service (Amazon ECS) and wants to ensure high availability. The company wants to be able to deploy updates to its application even if nodes in one Availability Zone are not accessible.
The expected request volume for the application is 100 requests per second, and each container task is able to serve at least 60 requests per second. The company set up Amazon ECS with a rolling update deployment type with the minimum healthy percent parameter set to 50% and the maximum percent set to
100%.
Which configuration of tasks and Availability Zones meets these requirements?

Answer options

• A. Deploy the application across two Availability Zones, with one task in each Availability Zone.
• B. Deploy the application across two Availability Zones, with two tasks in each Availability Zone.
• C. Deploy the application across three Availability Zones, with one task in each Availability Zone.
• D. Deploy the application across three Availability Zones, with two tasks in each Availability Zone.

Correct answer: D

Explanation

To handle 100 requests per second with each task serving 60, a minimum of 2 running tasks is required. With Option D (6 tasks total across 3 AZs), if one AZ fails, 4 tasks remain active, which is above the minimum healthy percent of 50% (3 tasks) and still provides more than enough capacity to handle the load during a rolling update. Other configurations either fail to provide the minimum required tasks during an outage or violate the rolling update parameters when one AZ is offline.