CLF-C02 Cloud Technology and Services Practice Question
A company runs a read-heavy web application on Amazon EC2 instances that queries an Amazon RDS database. As traffic grows, the database CPU utilization is consistently high, causing slow response times for users. The company wants to reduce the load on the database by caching frequently accessed query results. They need a fully managed, in-memory caching service that can be set up quickly and integrates with common programming languages. Which AWS service should they use?
⚠ Common exam trap
Many exam-takers confuse DAX (a DynamoDB-specific cache) with a general-purpose cache, or think CloudFront can cache database query results, when in fact ElastiCache is the correct service for caching RDS query outputs in a read-heavy application.
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
✓
Amazon ElastiCache
Amazon ElastiCache is a fully managed, in-memory caching service that supports Redis and Memcached, both of which integrate with common programming languages via standard client libraries. It can be deployed quickly to cache frequently accessed database query results, offloading read traffic from the Amazon RDS instance and reducing CPU utilization.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Amazon DynamoDB Accelerator (DAX)
Why it's wrong here
Amazon DynamoDB Accelerator (DAX) is a purpose-built in-memory cache for Amazon DynamoDB, not for Amazon RDS. It accelerates reads on DynamoDB tables by providing microsecond response times but cannot be attached to a relational database such as MySQL or PostgreSQL. Therefore, it is irrelevant to reducing RDS load in this EC2-hosted web application.
When this WOULD be correct
A company uses Amazon DynamoDB as its primary database and experiences high latency due to frequent reads. They need a fully managed, in-memory cache that integrates seamlessly with DynamoDB and supports common programming languages. In that scenario, DAX would be the correct answer.
- ✓
Amazon ElastiCache
Why this is correct
Amazon ElastiCache is a fully managed in-memory caching service that supports Redis and Memcached. It can be used to cache frequently accessed database query results, reducing the load on Amazon RDS and improving application response times.
- ✗
Amazon CloudFront
Why it's wrong here
Amazon CloudFront is a content delivery network that caches static and dynamic web content at edge locations to reduce latency for end users. It operates at the HTTP/CDN layer and cannot cache the results of database queries made by the application server, nor does it offload read requests from Amazon RDS. Its role is limited to distributing external-facing content, not internal database access.
When this WOULD be correct
A company wants to reduce latency for users worldwide by caching static web content (e.g., images, CSS, JavaScript) and serving it from edge locations. They need a global CDN that integrates with AWS origins like S3 or EC2. Amazon CloudFront would be the correct answer.
- ✗
Amazon S3 Transfer Acceleration
Why it's wrong here
Amazon S3 Transfer Acceleration uses AWS edge locations and optimized network paths to speed up large file uploads to Amazon S3 over long distances. It is designed to improve transfer throughput for object storage, not to cache database query results or reduce RDS read load. This makes it completely inapplicable to the described read-heavy web application scenario.
When this WOULD be correct
A company needs to accelerate uploads of large files to an S3 bucket from geographically distributed clients, and they require a fully managed service that uses AWS edge locations.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The CLF-C02 exam frequently reuses these exact scenarios with slightly different constraints.
✓Amazon ElastiCacheCorrect answer▾
Why this is correct
Amazon ElastiCache is a fully managed in-memory caching service that supports Redis and Memcached. It can be used to cache frequently accessed database query results, reducing the load on Amazon RDS and improving application response times.
✗Amazon DynamoDB Accelerator (DAX)Wrong answer — click to see why▾
Why this is wrong here
DAX is an in-memory cache for Amazon DynamoDB, not for Amazon RDS. The question specifies an RDS database, so DAX cannot be used to cache RDS query results.
★ When this WOULD be the correct answer
A company uses Amazon DynamoDB as its primary database and experiences high latency due to frequent reads. They need a fully managed, in-memory cache that integrates seamlessly with DynamoDB and supports common programming languages. In that scenario, DAX would be the correct answer.
Why candidates choose this
Candidates may confuse DAX as a general-purpose caching service due to its name containing 'Accelerator' and its in-memory nature, overlooking that it is tightly coupled with DynamoDB.
✗Amazon CloudFrontWrong answer — click to see why▾
Why this is wrong here
Amazon CloudFront is a content delivery network (CDN) that caches static and dynamic content at edge locations, not an in-memory caching service for database query results. It does not provide low-latency, in-memory caching for application-level data like RDS query results.
★ When this WOULD be the correct answer
A company wants to reduce latency for users worldwide by caching static web content (e.g., images, CSS, JavaScript) and serving it from edge locations. They need a global CDN that integrates with AWS origins like S3 or EC2. Amazon CloudFront would be the correct answer.
Why candidates choose this
Candidates may confuse caching at the edge (CDN) with in-memory caching, or think CloudFront can cache database query results because it supports dynamic content caching. They might overlook the requirement for a fully managed, in-memory cache that integrates with programming languages.
✗Amazon S3 Transfer AccelerationWrong answer — click to see why▾
Why this is wrong here
Amazon S3 Transfer Acceleration is designed to speed up uploads to S3 over long distances, not for caching database query results in memory.
★ When this WOULD be the correct answer
A company needs to accelerate uploads of large files to an S3 bucket from geographically distributed clients, and they require a fully managed service that uses AWS edge locations.
Why candidates choose this
Candidates may confuse 'acceleration' with 'caching' and think S3 Transfer Acceleration can speed up database queries, or they may associate it with content delivery caching similar to CloudFront.
Analysis generated from the official CLF-C02blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CLF-C02 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 CLF-C02 exam.