CLF-C02 Cloud Technology and Services Practice Question
A company runs a web application on Amazon EC2 instances that connect to a relational database. The application requires high database availability so that if the primary database instance fails, a standby instance automatically takes over without manual intervention. The company wants to minimize administrative overhead for database patching, backups, and replication. Which AWS service should the company use to meet these requirements?
⚠ Common exam trap
A common mix-up: candidates confuse Amazon RDS Multi-AZ with Amazon DynamoDB Global Tables, assuming both provide high availability for relational databases, but DynamoDB is NoSQL and does not support relational queries or the same failover model.
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 RDS Multi-AZ
Amazon RDS Multi-AZ provides high availability by automatically provisioning and maintaining a synchronous standby replica in a different Availability Zone. If the primary database instance fails, Amazon RDS automatically fails over to the standby, ensuring minimal downtime without manual intervention. Additionally, RDS handles patching, backups, and replication automatically, reducing administrative overhead.
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 Multi-AZ
Why this is correct
Correct. Amazon RDS Multi-AZ automatically provisions and maintains a synchronous standby replica in a different Availability Zone. If the primary instance fails, Amazon RDS automatically fails over to the standby, providing high availability. It also handles automated backups, patching, and replication.
- ✗
Amazon RDS Single-AZ
Why it's wrong here
Amazon RDS Single-AZ deployments run a single database instance in one Availability Zone, with no standby replica to take over if the primary instance fails. While automated backups and point-in-time recovery are available, they do not prevent downtime during an instance crash or AZ outage; recovery requires launching a new instance from a backup. Multi-AZ, by contrast, provisions a synchronous standby in a different AZ and automatically fails over, which is the high-availability capability the question asks for.
When this WOULD be correct
A company runs a development/test web application on Amazon EC2 that uses a relational database and wants to minimize costs while still using a managed database service. They do not require high availability or automatic failover.
- ✗
Amazon DynamoDB Global Tables
Why it's wrong here
Amazon DynamoDB Global Tables is a fully managed NoSQL key-value and document database service that replicates data across multiple AWS Regions for low-latency access and disaster recovery. However, the question specifies a relational database requiring SQL queries, joins, and ACID transactions, which DynamoDB does not support. Global Tables is not a relational database and cannot serve as a drop-in replacement for Amazon RDS Multi-AZ.
When this WOULD be correct
A company needs a globally distributed, multi-region, multi-active NoSQL database with automatic replication and high availability for a web application that can tolerate eventual consistency.
- ✗
Amazon S3
Why it's wrong here
Amazon S3 is an object storage service designed to store and retrieve arbitrary data as objects, not a relational database engine. It cannot process SQL queries, enforce schemas, or handle transactional DML operations, and it does not provide built-in automatic failover for a database primary. Although S3 offers high durability and availability, it is not an appropriate choice for the relational database tier of a web application.
When this WOULD be correct
A company needs to store and retrieve large amounts of unstructured data (e.g., images, videos, backups) with high durability and availability, and requires serverless storage with no database management overhead.
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 RDS Multi-AZCorrect answer▾
Why this is correct
Correct. Amazon RDS Multi-AZ automatically provisions and maintains a synchronous standby replica in a different Availability Zone. If the primary instance fails, Amazon RDS automatically fails over to the standby, providing high availability. It also handles automated backups, patching, and replication.
✗Amazon RDS Single-AZWrong answer — click to see why▾
Why this is wrong here
Amazon RDS Single-AZ does not provide automatic failover to a standby instance; if the primary fails, the database becomes unavailable until manual intervention restores it.
★ When this WOULD be the correct answer
A company runs a development/test web application on Amazon EC2 that uses a relational database and wants to minimize costs while still using a managed database service. They do not require high availability or automatic failover.
Why candidates choose this
Candidates may think Single-AZ is sufficient because they overlook the requirement for automatic failover, focusing only on the managed database aspect.
✗Amazon DynamoDB Global TablesWrong answer — click to see why▾
Why this is wrong here
Amazon DynamoDB Global Tables is a NoSQL database service, not a relational database, and the question specifies a relational database requirement.
★ When this WOULD be the correct answer
A company needs a globally distributed, multi-region, multi-active NoSQL database with automatic replication and high availability for a web application that can tolerate eventual consistency.
Why candidates choose this
Candidates may confuse 'Global Tables' with high availability and automatic failover, not realizing DynamoDB is NoSQL and not relational.
✗Amazon S3Wrong answer — click to see why▾
Why this is wrong here
Amazon S3 is an object storage service, not a relational database. It cannot provide the high availability, automatic failover, or relational database capabilities required for this web application.
★ When this WOULD be the correct answer
A company needs to store and retrieve large amounts of unstructured data (e.g., images, videos, backups) with high durability and availability, and requires serverless storage with no database management overhead.
Why candidates choose this
Candidates may confuse high availability and durability features of S3 with database availability, or think S3 can serve as a database due to its scalability and low cost.
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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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.