The answer is Amazon DynamoDB, the best NoSQL database for JSON documents with high availability. DynamoDB is the correct choice because it is a fully managed key-value and document database that natively stores JSON documents, supports frequent reads and writes with single-digit millisecond latency, and automatically replicates data across multiple Availability Zones to ensure high availability and durability. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of DynamoDB’s core strengths versus relational databases like RDS or other NoSQL options such as DocumentDB, which is MongoDB-compatible but not the default for high-availability JSON workloads. A common trap is choosing Amazon DocumentDB because it also handles JSON, but DynamoDB is the fully managed, serverless service with built-in multi-AZ replication and no operational overhead. Memory tip: think “DynamoDB = Dynamic Documents + DB” — it’s the go-to for JSON with automatic high availability.
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. 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 company needs to store JSON documents that are frequently read and written by a web application. The data must be highly available and durable across multiple Availability Zones. Which AWS database service meets these requirements?
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 provides single-digit millisecond performance at any scale. It stores JSON documents natively, supports frequent reads and writes, and offers built-in high availability and durability by automatically replicating data across multiple Availability Zones (AZs) in an AWS Region. This makes it the ideal choice for the described web application workload.
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
RDS for PostgreSQL is relational and requires schema definition, not ideal for flexible JSON documents.
✗
Amazon S3
Why it's wrong here
S3 is object storage, not a database; it lacks database features like transactions.
✓
Amazon DynamoDB
Why this is correct
DynamoDB is a fully managed NoSQL database that supports JSON documents and offers multi-AZ durability.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon ElastiCache for Redis
Why it's wrong here
ElastiCache is an in-memory cache, not designed for durable storage.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Amazon S3's high durability and availability with database capabilities, overlooking that S3 is an object store with higher latency and no native query support, while DynamoDB is purpose-built for low-latency, high-throughput document storage with ACID transactions via DynamoDB Transactions.
Detailed technical explanation
How to think about this question
DynamoDB achieves high availability and durability by automatically replicating data synchronously across three AZs in a Region using its internal distributed storage engine. Under the hood, each item is stored on multiple storage nodes across different AZs, and writes are acknowledged only after the data is durably written to all replicas. In a real-world scenario, if a web application requires consistent single-digit millisecond response times for both reads and writes with automatic scaling to handle traffic spikes, DynamoDB’s use of consistent hashing and SSD-backed storage ensures predictable performance without manual sharding.
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
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Data Store Management — This question tests Data Store Management — 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 a fully managed NoSQL key-value and document database that provides single-digit millisecond performance at any scale. It stores JSON documents natively, supports frequent reads and writes, and offers built-in high availability and durability by automatically replicating data across multiple Availability Zones (AZs) in an AWS Region. This makes it the ideal choice for the described web application workload.
What should I do if I get this DEA-C01 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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Question Discussion
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