The correct strategies are implementing a caching layer such as ElastiCache and deploying read replicas for the relational database. Caching reduces the load on the database by serving frequently accessed data from an in-memory store, dramatically improving response times for millions of concurrent users. Read replicas offload read-heavy traffic from the primary database instance, allowing the system to scale horizontally for read queries without degrading write performance. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how to combine stateless caching with database read scaling to handle massive concurrency—a common trap is choosing only one strategy or misapplying read replicas for write-heavy workloads. For memory, think “Cache first, then replicate reads,” or use the mnemonic “CRR: Cache, Replicas, Reads.”
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new solutions. 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 designing a web application that must support millions of concurrent users. The application uses a RESTful API frontend and a relational database backend. Which TWO strategies should be implemented to improve scalability?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement read replicas for the database.
Read replicas (Option C) offload read traffic from the primary database instance, allowing the relational database to handle a higher volume of concurrent read queries without degrading write performance. This directly improves scalability for read-heavy workloads common in web applications.
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 Amazon SQS to queue database write requests.
Why it's wrong here
SQS decouples but does not directly improve database scalability.
✗
Use sticky sessions (session affinity) on the load balancer.
Why it's wrong here
Sticky sessions can reduce scalability by preventing even load distribution.
✓
Implement read replicas for the database.
Why this is correct
Read replicas offload read traffic from the primary database.
Related concept
Read the scenario before looking for a memorised answer.
✓
Implement a caching layer such as ElastiCache.
Why this is correct
Caching reduces database load and improves response times.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a single large EC2 instance for the database.
Why it's wrong here
Vertical scaling has limits; horizontal scaling is better.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse queuing (SQS) with database scalability, but SQS does not increase database throughput—it only buffers requests, which can lead to backpressure and eventual inconsistency if not carefully designed.
Detailed technical explanation
How to think about this question
Read replicas in Amazon RDS use asynchronous replication from the primary instance to one or more read-only copies, which can be promoted to standalone instances if needed. A caching layer like ElastiCache (Option D) reduces database load by serving frequently accessed data from in-memory stores (e.g., Redis or Memcached), cutting latency and read I/O. In practice, combining read replicas for persistent data and caching for hot data is a proven pattern for scaling relational databases under high concurrency.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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.
Design for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement read replicas for the database. — Read replicas (Option C) offload read traffic from the primary database instance, allowing the relational database to handle a higher volume of concurrent read queries without degrading write performance. This directly improves scalability for read-heavy workloads common in web applications.
What should I do if I get this SAP-C02 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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