The correct design is to use auto-scaling for the application tier and read replicas for the database. This works because a stateless application tier can be scaled horizontally by adding or removing instances based on real-time metrics like CPU utilization or request count, directly handling sudden traffic spikes without over-provisioning. For the read-heavy database tier, read replicas offload SELECT queries from the primary database, improving read throughput and cost efficiency by scaling horizontally only when needed, while the primary handles occasional writes. On the CompTIA Cloud+ CV0-004 exam, this scenario tests your understanding of elasticity for stateless application tier and read-heavy database patterns, often appearing in multi-tier architecture questions. A common trap is proposing database vertical scaling or a single database instance, which fails to address read-heavy loads cost-effectively. Remember the memory tip: “Stateless scales out, read-heavy reads out”—auto-scaling handles the app’s stateless bursts, while read replicas distribute the database’s read load.
CV0-004 Cloud Architecture and Design Practice Question
This CV0-004 practice question tests your understanding of cloud architecture and 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 cloud architect is designing a multi-tier web application that must handle sudden traffic spikes. The application layer is stateless, and the database layer is read-heavy with occasional writes. Which design best meets the requirement for elasticity and cost efficiency?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use auto-scaling for the application tier and read replicas for the database
Option A is correct because auto-scaling the stateless application tier dynamically adds or removes instances based on CPU or request metrics, directly handling traffic spikes without over-provisioning. For the read-heavy database tier, read replicas offload SELECT queries from the primary database, improving read throughput and cost efficiency by scaling horizontally only when needed, while the primary handles occasional writes.
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.
✓
Use auto-scaling for the application tier and read replicas for the database
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Implement auto-scaling for the database tier and use a larger application instance
Why it's wrong here
Auto-scaling databases is complex and not typically read-heavy optimized; vertical scaling is less elastic.
✗
Use a load balancer to distribute traffic to multiple database instances
Why it's wrong here
Load balancers are for application traffic, not for distributing database writes; databases need replication.
✗
Deploy large application and database instances to handle peak load
Why it's wrong here
Overprovisioning is not cost-efficient and does not scale down during low demand.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that auto-scaling applies equally to all tiers, but the trap here is that databases are stateful and require careful replication strategies (like read replicas) rather than simple instance scaling, and candidates may confuse load balancers with database replication mechanisms.
Detailed technical explanation
How to think about this question
Auto-scaling for stateless tiers relies on horizontal scaling via launch templates and target tracking scaling policies (e.g., based on average CPU utilization > 70%). Read replicas in AWS RDS use asynchronous replication from the primary to up to 15 read replicas, which can be promoted to primary in a failover, but they do not handle writes—this is critical for read-heavy workloads. In a real-world scenario, a flash sale might trigger a 10x traffic spike; auto-scaling the app tier adds instances in minutes, while read replicas absorb the query load, preventing the primary from becoming a bottleneck.
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 practitioner preparing for the CV0-004 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
Cloud Architecture and Design — This question tests Cloud Architecture and Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use auto-scaling for the application tier and read replicas for the database — Option A is correct because auto-scaling the stateless application tier dynamically adds or removes instances based on CPU or request metrics, directly handling traffic spikes without over-provisioning. For the read-heavy database tier, read replicas offload SELECT queries from the primary database, improving read throughput and cost efficiency by scaling horizontally only when needed, while the primary handles occasional writes.
What should I do if I get this CV0-004 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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