The correct answers are Amazon DynamoDB and Amazon DocumentDB, as both are fully managed database services that natively support JSON documents with variable schema while providing high availability and automatic scaling for microservices. DynamoDB excels as a serverless, low-latency key-value and document store with on-demand capacity mode that scales automatically, while DocumentDB offers MongoDB-compatible document storage with multi-AZ replication and auto-scaling storage. On the AWS Certified Database Specialty DBS-C01 exam, this question tests your ability to distinguish between NoSQL document databases that meet microservices requirements—a common trap is assuming only one service fits, when both DynamoDB and DocumentDB satisfy the criteria for variable-schema JSON documents. Remember the memory tip: "Dynamo for speed, DocDB for MongoDB compatibility"—both handle JSON, but DynamoDB is ideal for serverless microservices needing millisecond latency, while DocumentDB suits workloads requiring MongoDB ecosystem tools.
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 is building a microservices architecture and needs a database for a service that stores JSON documents with variable schema. The database must support high availability and automatic scaling. Which TWO services meet these requirements? (Choose two.)
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 correct because it is a fully managed NoSQL key-value and document database that natively supports JSON documents with variable schema, offers high availability through multi-AZ replication, and provides automatic scaling via its on-demand capacity mode or auto-scaling policies. It is ideal for microservices architectures that require low-latency, serverless, and elastic throughput.
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 ElastiCache for Redis
Why it's wrong here
ElastiCache is a cache, not a primary database.
✓
Amazon DynamoDB
Why this is correct
DynamoDB supports JSON documents, high availability, and auto scaling.
Related concept
Read the scenario before looking for a memorised answer.
✓
Amazon DocumentDB
Why this is correct
DocumentDB is MongoDB-compatible, supports JSON, and provides automatic scaling.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon Neptune
Why it's wrong here
Neptune is a graph database, not document-oriented.
✗
Amazon RDS for MySQL
Why it's wrong here
RDS is relational and does not natively support variable schema JSON.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the misconception that any database supporting JSON (like MySQL with JSON data type) qualifies as a document database for variable schema workloads, but the key differentiator is automatic scaling and native document store capabilities, which DynamoDB and DocumentDB provide, while RDS does not.
Detailed technical explanation
How to think about this question
DynamoDB stores JSON documents as items in tables, with each item's attributes defined by a primary key and optional sort key, allowing schema flexibility at the item level. Under the hood, DynamoDB partitions data across multiple nodes using consistent hashing, and its auto-scaling adjusts read/write capacity based on traffic patterns via AWS Application Auto Scaling, while on-demand mode eliminates capacity planning entirely. In real-world microservices, DynamoDB's single-digit millisecond latency and DAX (DynamoDB Accelerator) caching layer make it a common choice for event-driven, serverless architectures.
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.
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.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — 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 correct because it is a fully managed NoSQL key-value and document database that natively supports JSON documents with variable schema, offers high availability through multi-AZ replication, and provides automatic scaling via its on-demand capacity mode or auto-scaling policies. It is ideal for microservices architectures that require low-latency, serverless, and elastic throughput.
What should I do if I get this DBS-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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This DBS-C01 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 DBS-C01 exam.
Question Discussion
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