The correct configuration is to deploy a Redis cluster with cluster mode enabled and replica nodes in a different Availability Zone. This setup provides true multi-AZ high availability by combining sharding for horizontal scaling with cross-AZ replication, ensuring that if the primary node or an entire Availability Zone fails, a replica in another AZ automatically promotes to primary with minimal downtime. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding that cluster mode enabled is required for automatic failover across AZs, while a simple replication group without clustering only supports manual promotion. A common trap is assuming a single-shard Redis (non-clustered) with Multi-AZ enabled is sufficient, but that configuration lacks the sharding and automatic failover guarantees needed for session data resilience. Memory tip: think “cluster mode = automatic cross-AZ failover; no cluster = manual failover only.”
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 using Amazon ElastiCache for Redis as a caching layer for frequently accessed data. The application needs to support caching of session data that must be highly available across multiple Availability Zones. Which ElastiCache configuration should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Deploy a Redis cluster with cluster mode enabled and replica nodes in a different Availability Zone.
Option D is correct because deploying a Redis cluster with cluster mode enabled and replica nodes in a different Availability Zone provides both high availability and automatic failover for session data. ElastiCache for Redis with cluster mode enabled supports sharding and replication, allowing replica nodes to be placed in a separate AZ to survive an AZ failure. This configuration ensures session data remains accessible even if the primary node or an entire AZ becomes unavailable, meeting the requirement for multi-AZ high availability.
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.
✗
Deploy a single Redis node in one Availability Zone.
Why it's wrong here
A single node has no high availability; if it fails, data is lost.
✗
Deploy a Redis cluster with cluster mode disabled.
Why it's wrong here
Without cluster mode, there is only one shard; replicas can be added but not for automatic failover in all configurations.
✗
Deploy a Memcached cluster with multiple nodes.
Why it's wrong here
Memcached does not support replication; high availability is limited.
✓
Deploy a Redis cluster with cluster mode enabled and replica nodes in a different Availability Zone.
Why this is correct
Cluster mode with replicas across AZs provides high availability and automatic failover.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse cluster mode enabled/disabled with multi-AZ support, mistakenly thinking that cluster mode disabled cannot place replicas in different AZs, when in fact both modes support multi-AZ replication, but the question's requirement for 'highly available across multiple Availability Zones' and the specific wording of the correct answer point to cluster mode enabled as the intended solution for a Redis cluster that can scale and survive AZ failures.
Detailed technical explanation
How to think about this question
Under the hood, ElastiCache for Redis with cluster mode enabled uses a distributed architecture where data is partitioned across up to 500 shards, each with a primary and up to 5 replicas. Replica nodes in a different AZ use synchronous replication within the shard to ensure data consistency, and automatic failover is handled by the Redis engine's Sentinel-like mechanism integrated into ElastiCache. In a real-world scenario, if the primary node in AZ-a fails, ElastiCache promotes a replica in AZ-b to primary within seconds, and the application reconnects via the cluster's configuration endpoint, ensuring zero data loss for session data that is typically small and frequently accessed.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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: Deploy a Redis cluster with cluster mode enabled and replica nodes in a different Availability Zone. — Option D is correct because deploying a Redis cluster with cluster mode enabled and replica nodes in a different Availability Zone provides both high availability and automatic failover for session data. ElastiCache for Redis with cluster mode enabled supports sharding and replication, allowing replica nodes to be placed in a separate AZ to survive an AZ failure. This configuration ensures session data remains accessible even if the primary node or an entire AZ becomes unavailable, meeting the requirement for multi-AZ high availability.
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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Question Discussion
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