- A
Amazon RDS for PostgreSQL
Why wrong: Amazon RDS is a relational database service that is not optimized for key-value access patterns. It scales primarily vertically (larger instances) and does not provide the same horizontal scalability and low-latency performance as a NoSQL database for this use case.
- B
Amazon Redshift
Why wrong: Amazon Redshift is a data warehouse service designed for analytical queries on large datasets. It is not suitable for real-time, low-latency key-value lookups and does not support the access patterns required for player profiles and session state.
- C
Amazon DynamoDB
Correct. Amazon DynamoDB is a fully managed NoSQL key-value and document database that provides single-digit millisecond latency at any scale. It scales horizontally, supports auto scaling, and offers built-in multi-AZ replication for high availability and durability.
- D
Amazon ElastiCache for Redis
Why wrong: Amazon ElastiCache is an in-memory caching service that provides low latency but is not designed as a durable primary datastore. While it can store session data, it lacks the persistence, durability guarantees, and managed scaling features that DynamoDB offers for a primary database.
CLF-C02 Cloud Technology and Services Practice Question
This CLF-C02 practice question tests your understanding of cloud technology and services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A gaming company operates a mobile game with millions of active users. The game stores player profiles and session state in a key-value database. The database must provide single-digit millisecond latency for read and write operations at any scale. The company expects traffic to grow unpredictably, and the database must scale horizontally without downtime. The company wants a fully managed, highly available solution with built-in replication across multiple Availability Zones. Which AWS service should the company use?
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 the correct choice because it is a fully managed, serverless, NoSQL key-value database that delivers single-digit millisecond latency at any scale. It supports horizontal scaling via automatic partitioning and replication across multiple Availability Zones (AZs) for high availability, with no downtime required for scaling. This directly matches the gaming company's requirements for low-latency reads/writes, unpredictable traffic growth, and built-in multi-AZ replication.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 RDS for PostgreSQL
Why it's wrong here
Amazon RDS is a relational database service that is not optimized for key-value access patterns. It scales primarily vertically (larger instances) and does not provide the same horizontal scalability and low-latency performance as a NoSQL database for this use case.
When this WOULD be correct
A company needs a fully managed relational database with SQL support, ACID transactions, and multi-AZ replication for a traditional web application with predictable traffic patterns. The workload requires complex joins and queries, and latency requirements are in the tens of milliseconds rather than single-digit.
- ✗
Amazon Redshift
Why it's wrong here
Amazon Redshift is a data warehouse service designed for analytical queries on large datasets. It is not suitable for real-time, low-latency key-value lookups and does not support the access patterns required for player profiles and session state.
When this WOULD be correct
A company needs to run complex SQL queries and aggregations on petabytes of structured data for business intelligence and reporting, with high performance for analytical workloads. The database must be fully managed and support columnar storage and massively parallel processing.
- ✓
Amazon DynamoDB
Why this is correct
Correct. Amazon DynamoDB is a fully managed NoSQL key-value and document database that provides single-digit millisecond latency at any scale. It scales horizontally, supports auto scaling, and offers built-in multi-AZ replication for high availability and durability.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Amazon ElastiCache for Redis
Why it's wrong here
Amazon ElastiCache is an in-memory caching service that provides low latency but is not designed as a durable primary datastore. While it can store session data, it lacks the persistence, durability guarantees, and managed scaling features that DynamoDB offers for a primary database.
When this WOULD be correct
A company needs a low-latency, in-memory data store for caching frequently accessed data, such as session state or database query results, to reduce load on a primary database. The solution must support sub-millisecond response times and can tolerate data loss on failure.
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 DynamoDBCorrect answer▾
Why this is correct
Correct. Amazon DynamoDB is a fully managed NoSQL key-value and document database that provides single-digit millisecond latency at any scale. It scales horizontally, supports auto scaling, and offers built-in multi-AZ replication for high availability and durability.
✗Amazon RDS for PostgreSQLWrong answer — click to see why▾
Why this is wrong here
Amazon RDS for PostgreSQL is a relational database that does not natively support horizontal scaling (sharding) without significant application changes, and it cannot guarantee single-digit millisecond latency at any scale for key-value workloads. It also requires manual effort for multi-AZ replication and does not provide the fully managed, auto-scaling key-value store required.
★ When this WOULD be the correct answer
A company needs a fully managed relational database with SQL support, ACID transactions, and multi-AZ replication for a traditional web application with predictable traffic patterns. The workload requires complex joins and queries, and latency requirements are in the tens of milliseconds rather than single-digit.
Why candidates choose this
Candidates may confuse key-value databases with relational databases or assume that RDS can be used for any data storage need, overlooking the specific requirements for horizontal scaling and low latency at scale.
✗Amazon RedshiftWrong answer — click to see why▾
Why this is wrong here
Amazon Redshift is a data warehouse for analytical queries on large datasets, not a low-latency key-value store. It cannot provide single-digit millisecond read/write latency or scale horizontally for real-time transactional workloads.
★ When this WOULD be the correct answer
A company needs to run complex SQL queries and aggregations on petabytes of structured data for business intelligence and reporting, with high performance for analytical workloads. The database must be fully managed and support columnar storage and massively parallel processing.
Why candidates choose this
Candidates may confuse Redshift's high-performance capabilities with low-latency requirements, or assume that any AWS database service can handle key-value workloads due to its scalability features.
✗Amazon ElastiCache for RedisWrong answer — click to see why▾
Why this is wrong here
Amazon ElastiCache for Redis is an in-memory cache, not a durable key-value database. It lacks built-in replication across multiple Availability Zones for high availability and does not provide the fully managed, horizontally scalable key-value store with single-digit millisecond latency required for this use case.
★ When this WOULD be the correct answer
A company needs a low-latency, in-memory data store for caching frequently accessed data, such as session state or database query results, to reduce load on a primary database. The solution must support sub-millisecond response times and can tolerate data loss on failure.
Why candidates choose this
Candidates may confuse ElastiCache for Redis as a key-value database due to its key-value data model and low latency, overlooking that it is primarily a cache and not a durable, fully managed database with built-in replication across AZs.
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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Amazon ElastiCache for Redis with a durable database, but it is an in-memory cache that lacks native multi-AZ replication for persistence and is not designed as a primary key-value store for session state that must survive node failures.
Detailed technical explanation
How to think about this question
DynamoDB achieves single-digit millisecond latency through its distributed architecture where data is automatically partitioned across multiple storage nodes using consistent hashing, and each partition is replicated across three AZs within an AWS Region. The service uses SSD-backed storage and a write-ahead log to ensure durability, while its adaptive capacity feature automatically adjusts partitions as traffic grows, eliminating the need for manual re-sharding. In a real-world gaming scenario, DynamoDB can handle millions of concurrent requests for player session data by using DAX (DynamoDB Accelerator) for microsecond caching, but the base service already meets the stated latency requirements.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this CLF-C02 question test?
Cloud Technology and Services — This question tests Cloud Technology and Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Amazon DynamoDB — Amazon DynamoDB is the correct choice because it is a fully managed, serverless, NoSQL key-value database that delivers single-digit millisecond latency at any scale. It supports horizontal scaling via automatic partitioning and replication across multiple Availability Zones (AZs) for high availability, with no downtime required for scaling. This directly matches the gaming company's requirements for low-latency reads/writes, unpredictable traffic growth, and built-in multi-AZ replication.
What should I do if I get this CLF-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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.
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