Question 1,028 of 302
SAA-C03 Design High-Performing Architectures Practice Question
An Aurora PostgreSQL cluster is experiencing high read latency because 85% of traffic consists of read-only queries. The write workload must stay on the writer instance, and the team wants to offload reads without changing the application’s core query patterns. What is the best architectural option?
⚠ Common exam trap
Many exam-takers confuse Multi-AZ standby instances (which are passive and cannot serve reads) with Aurora reader replicas (which are active and can serve reads), leading them to incorrectly select Option C.
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
✓
Add Aurora reader instances (read replicas) and route read queries to the reader endpoint while keeping writes on the writer endpoint.
Adding Aurora reader instances (read replicas) and routing read queries to the reader endpoint offloads read traffic from the writer instance without altering application query patterns. Aurora reader endpoints automatically distribute read-only connections across all replicas, reducing latency on the writer while keeping writes on the writer instance. This directly addresses the 85% read-heavy workload without requiring application changes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the writer instance size so it can handle more reads and writes simultaneously.
Why it's wrong here
Scaling the writer increases resources, but it does not isolate read workload from write workload. With a heavily read traffic pattern, the writer still becomes the bottleneck due to shared compute/storage resources for both reads and writes.
When this WOULD be correct
This option would be correct if the question stated that the cluster is CPU-bound on the writer due to a mix of reads and writes, and the application cannot tolerate any read replica lag or connection routing changes, requiring a vertical scaling approach.
- ✓
Add Aurora reader instances (read replicas) and route read queries to the reader endpoint while keeping writes on the writer endpoint.
Why this is correct
Aurora reader instances are designed for exactly this pattern: they provide dedicated compute capacity for read-only workloads. By sending read queries to the reader endpoint and keeping writes on the writer endpoint, the cluster can scale read performance without forcing reads to contend with write processing on the writer.
- ✗
Enable Multi-AZ failover only and rely on the standby to serve reads in normal operation.
Why it's wrong here
Multi-AZ standby primarily provides high availability and failover behavior. It is not the same as adding dedicated reader capacity for steady-state read scaling, and it is not intended as a normal operational read offload path.
When this WOULD be correct
For a non-Aurora RDS database (e.g., RDS for MySQL or PostgreSQL) where you need high availability and want to offload read traffic to a standby, enabling Multi-AZ with the 'standby can serve reads' option (if supported) would be correct. The question would specify a single-instance RDS DB with Multi-AZ and the need to use the standby for reads.
- ✗
Move the read workload to ElastiCache Redis while keeping DynamoDB as the SQL data source.
Why it's wrong here
ElastiCache is a caching layer and Redis does not replace Aurora PostgreSQL SQL query execution for arbitrary read patterns without additional application/data redesign. The scenario asks for offloading reads from Aurora while keeping core query patterns, which aligns with Aurora readers rather than changing the data architecture.
When this WOULD be correct
This option would be correct in a scenario where the application uses a NoSQL database like DynamoDB as its primary data store, experiences high read traffic, and can tolerate eventual consistency. The team wants to offload reads without altering query patterns, and using ElastiCache Redis as a caching layer in front of DynamoDB would reduce read latency.
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 SAA-C03 exam frequently reuses these exact scenarios with slightly different constraints.
✓Add Aurora reader instances (read replicas) and route read queries to the reader endpoint while keeping writes on the writer endpoint.Correct answer▾
Why this is correct
Aurora reader instances are designed for exactly this pattern: they provide dedicated compute capacity for read-only workloads. By sending read queries to the reader endpoint and keeping writes on the writer endpoint, the cluster can scale read performance without forcing reads to contend with write processing on the writer.
✗Increase the writer instance size so it can handle more reads and writes simultaneously.Wrong answer — click to see why▾
Why this is wrong here
Increasing the writer instance size does not offload reads; it only scales the single writer instance, which still handles all read traffic and does not reduce read latency from high read concurrency.
★ When this WOULD be the correct answer
This option would be correct if the question stated that the cluster is CPU-bound on the writer due to a mix of reads and writes, and the application cannot tolerate any read replica lag or connection routing changes, requiring a vertical scaling approach.
Why candidates choose this
Candidates may think that a larger instance can handle more total throughput, overlooking that read replicas are specifically designed to offload read traffic and reduce latency for read-heavy workloads.
✗Enable Multi-AZ failover only and rely on the standby to serve reads in normal operation.Wrong answer — click to see why▾
Why this is wrong here
In Aurora, a Multi-AZ standby (writer failover target) does not serve read traffic; it is only used for failover. To offload reads, you need dedicated reader instances with a separate reader endpoint.
★ When this WOULD be the correct answer
For a non-Aurora RDS database (e.g., RDS for MySQL or PostgreSQL) where you need high availability and want to offload read traffic to a standby, enabling Multi-AZ with the 'standby can serve reads' option (if supported) would be correct. The question would specify a single-instance RDS DB with Multi-AZ and the need to use the standby for reads.
Why candidates choose this
Candidates may confuse Aurora's Multi-AZ with RDS Multi-AZ, or incorrectly assume that a standby can handle read requests in normal operation, similar to read replicas.
✗Move the read workload to ElastiCache Redis while keeping DynamoDB as the SQL data source.Wrong answer — click to see why▾
Why this is wrong here
Option D is wrong because it suggests using ElastiCache Redis with DynamoDB as the SQL data source, but the question specifies an Aurora PostgreSQL cluster. DynamoDB is a NoSQL database, not a SQL data source, and this approach would require significant application changes to query patterns, violating the constraint of not changing core query patterns.
★ When this WOULD be the correct answer
This option would be correct in a scenario where the application uses a NoSQL database like DynamoDB as its primary data store, experiences high read traffic, and can tolerate eventual consistency. The team wants to offload reads without altering query patterns, and using ElastiCache Redis as a caching layer in front of DynamoDB would reduce read latency.
Why candidates choose this
Candidates may choose this option because they recognize that caching (ElastiCache) is a common solution for read-heavy workloads, and they might overlook the specific database type (Aurora PostgreSQL vs. DynamoDB) or assume that any caching layer can be seamlessly integrated without considering the underlying data store compatibility.
Analysis generated from the official SAA-C03blueprint 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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Last reviewed: Jun 11, 2026
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