SAP-C02 Design for New Solutions Practice Question
A company is building a new application that will run on AWS Lambda. The application needs to store and retrieve user preferences in a key-value format. The data is accessed frequently and must be highly available. The company expects low latency for reads and writes. Which AWS service should be used as the data store?
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 DynamoDB
Amazon DynamoDB is a fully managed NoSQL key-value and document database that delivers single-digit millisecond performance at any scale. It is designed for low-latency, high-availability access, making it ideal for storing and retrieving user preferences in a key-value format. Option A: Amazon S3 is object storage, not a key-value store, and is not optimized for low-latency reads and writes for small objects. Option B: Amazon ElastiCache for Memcached is an in-memory key-value store, but it is not persistent and typically used for caching, not as a primary data store for persistent user preferences. Option C: Amazon RDS for PostgreSQL is a relational database, which requires schema definition and is not optimized for simple key-value access patterns.
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 S3
Why it's wrong here
Amazon S3 is object storage, not a key-value store, and is not optimized for low-latency reads and writes for small objects, especially for frequent access patterns.
- ✗
Amazon ElastiCache for Memcached
Why it's wrong here
Amazon ElastiCache for Memcached is an in-memory key-value store, but it is not persistent and is typically used for caching, not as a primary data store for persistent user preferences.
- ✗
Amazon RDS for PostgreSQL
Why it's wrong here
Amazon RDS for PostgreSQL is a relational database, which requires schema definition and is not optimized for simple key-value access patterns, often resulting in higher latency for simple key lookups.
- ✓
Amazon DynamoDB
Why this is correct
Amazon DynamoDB is a fully managed NoSQL key-value and document database that provides single-digit millisecond latency at any scale, with built-in high availability and durability, making it the best choice for this use case.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAP-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 SAP-C02 exam.