SAA-C03 Design High-Performing Architectures Practice Question
A logistics company runs a REST API on Amazon ECS using the Fargate launch type behind an Application Load Balancer. The API's response times are acceptable, but the operations team wants to reduce the number of database calls per request by caching frequently accessed reference data in memory inside the tasks. The data changes infrequently and slight staleness is acceptable. Which approach best meets these requirements?
⚠ Common exam trap
The trap here is treating any cache, such as ElastiCache, as equivalent to in-process caching, when external caches still require a network round trip per request.
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
✓
Implement an in-process cache in the application code that loads reference data at task startup and refreshes it periodically.
Caching reference data in the application's own process memory means each request is served locally with no database or network call, which is the most direct way to reduce per-request database calls. Because the data is small, changes rarely, and tolerates slight staleness, periodic refresh is simple and effective. External caches like Redis or Memcached still require a network call, and EFS is storage rather than memory.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Store the reference data in an Amazon ElastiCache for Redis cluster and have tasks query it on each request.
Why it's wrong here
ElastiCache for Redis is an external cache, so tasks still make a network call per request to retrieve the data, which does not eliminate database calls as effectively as in-memory caching and adds a dependency. It also introduces a separate cluster to manage and pay for. The requirement is to cache in memory inside the tasks, which Redis does not satisfy.
- ✓
Implement an in-process cache in the application code that loads reference data at task startup and refreshes it periodically.
Why this is correct
An in-process cache keeps the reference data in the task's own memory, so requests are served without any database call or network hop. Since the data changes infrequently and slight staleness is acceptable, a periodic refresh is sufficient and simple. This directly satisfies the goal of reducing database calls per request while using the Fargate tasks' memory, with no additional managed service required.
- ✗
Enable Amazon ElastiCache for Memcached and configure automatic discovery of cache nodes.
Why it's wrong here
Memcached is again an external cache requiring a network round trip per lookup, so it does not eliminate database calls as directly as in-process memory. Auto discovery simplifies node management but does not change the fundamental fact that the data lives outside the task. The scenario asks for in-memory caching inside the tasks, which an external Memcached cluster does not fulfill.
- ✗
Use the ECS task definition to mount an Amazon EFS file system containing the reference data.
Why it's wrong here
EFS provides shared file storage, not an in-memory cache, so each read still involves network I/O to the file system. It does not reduce database calls in the way an in-process memory cache does, and it adds latency compared with local memory. The scenario explicitly asks for in-memory caching within the tasks, which EFS does not provide.
Go deeper
Related to this question
About these practice questions
This SAA-C03 question is part of Courseiva's 935-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This SAA-C03 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 SAA-C03 exam.