CV0-004 Cloud Architecture and Design Practice Question
A cloud engineer is sizing a relational database for an application with unpredictable read volume that spikes sharply during business hours. The database must scale read capacity without downtime and without changing the application's connection string. Which approach should the engineer use?
⚠ Common exam trap
A common mix-up: candidates confuse a multi-AZ standby, which is passive and used only for failover, with a read replica, which actively serves read queries.
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 read replicas behind a database-aware proxy or reader endpoint so reads are distributed across replicas.
Read replicas let a relational database scale read capacity horizontally while the primary continues handling writes. Because replicas can be added or removed online and a reader endpoint or proxy keeps a stable address, the application does not need a new connection string and experiences no downtime during scaling.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Vertically scale the primary database instance to a larger size during peak hours.
Why it's wrong here
Vertical scaling increases the primary's capacity, but it does not distribute read load and typically requires a restart or failover, which is downtime. It also has a ceiling and cannot match sudden, unpredictable spikes efficiently. The scenario explicitly requires scaling without downtime and without changing the connection string, so resizing the primary fails those constraints.
- ✗
Enable a multi-AZ standby and direct read queries to the standby instance.
Why it's wrong here
A multi-AZ standby exists for high availability failover, not for serving read traffic. It receives synchronous replication from the primary but is not accessible for normal queries; directing reads to it is not supported and would not scale capacity. This design protects availability, not read throughput, so it does not solve the unpredictable read spike.
- ✓
Add read replicas behind a database-aware proxy or reader endpoint so reads are distributed across replicas.
Why this is correct
Read replicas offload read traffic from the primary and can be added or removed while the database stays online. A reader endpoint or proxy presents a stable address, so the application keeps the same connection string while read capacity scales horizontally. This directly addresses unpredictable read spikes without downtime or application changes.
- ✗
Increase the database's storage volume size to improve read throughput.
Why it's wrong here
Storage size can affect IOPS limits on some volume types, but it does not distribute query load across additional compute resources and cannot be changed instantaneously without downtime in many engines. The bottleneck here is read concurrency, not raw capacity, so adding storage does not address the business-hours read spikes described.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This CV0-004 practice question is part of Courseiva's free CompTIA 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 CV0-004 exam.