The answer is to add read replicas across zones. This configuration is correct because Cloud SQL read replicas use asynchronous replication to maintain a copy of the primary instance, allowing you to offload read-heavy workloads by distributing SELECT queries across multiple replicas. By placing replicas in different zones, you also gain high availability and fault tolerance, ensuring that read capacity remains resilient even if one zone experiences an outage. On the Google Professional Cloud Developer exam, this scenario tests your understanding of scaling strategies for managed databases—specifically that read replicas scale reads horizontally, while vertical scaling (increasing machine size) is less efficient for read-heavy patterns. A common trap is confusing read replicas with failover replicas; remember that failover replicas are for high availability, not for scaling read traffic. Memory tip: “Read replicas read, failover replicas fail over.”
PCD Practice Question: Designing highly scalable, available, and reliable cloud-native applications
This PCD practice question tests your understanding of designing highly scalable, available, and reliable cloud-native applications. 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.
An application uses Cloud SQL for read-heavy workloads. To scale reads, which configuration is best?
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
✓
Add read replicas across zones
Read replicas in Cloud SQL allow you to offload read traffic from the primary instance to one or more replica instances, which are kept in sync using asynchronous replication. This configuration directly scales read capacity by distributing SELECT queries across replicas, making it the best choice for read-heavy workloads.
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 connection pooling
Why it's wrong here
Connection pooling reduces connection overhead but does not increase read throughput.
✗
Enable high availability with standby
Why it's wrong here
High availability provides failover, but the standby does not serve reads.
✓
Add read replicas across zones
Why this is correct
Read replicas offload read traffic from the primary, scaling read capacity.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable automatic storage increase
Why it's wrong here
Storage increase prevents running out of space, but does not improve read performance.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that high availability (standby) or connection pooling can scale read capacity, when in fact they serve different purposes—HA ensures durability, pooling reduces connection churn, and only read replicas directly increase read throughput.
Detailed technical explanation
How to think about this question
Cloud SQL read replicas use MySQL or PostgreSQL native asynchronous replication, where the replica applies changes from the primary's binary log (binlog) or write-ahead log (WAL). Under heavy read loads, replicas can be placed in different zones to improve regional read latency and resilience. A real-world scenario is a reporting application that runs complex analytical queries on replicas, preventing those queries from degrading primary write performance.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Designing highly scalable, available, and reliable cloud-native applications — This question tests Designing highly scalable, available, and reliable cloud-native applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add read replicas across zones — Read replicas in Cloud SQL allow you to offload read traffic from the primary instance to one or more replica instances, which are kept in sync using asynchronous replication. This configuration directly scales read capacity by distributing SELECT queries across replicas, making it the best choice for read-heavy workloads.
What should I do if I get this PCD 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A web application uses Cloud SQL for MySQL. The team expects a sudden spike in read-only traffic from a reporting tool. What should they use to offload read queries?
easy
A.Automatic storage increase
B.Cross-region replication
✓ C.Read replicas
D.Failover replica
Why C: Read replicas in Cloud SQL for MySQL allow you to offload read traffic from the primary instance by creating one or more read-only copies. This is the correct approach for handling a sudden spike in read-only queries from a reporting tool, as it distributes the load without affecting write performance or requiring application changes beyond updating the connection string.
Last reviewed: Jun 25, 2026
Question Discussion
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This PCD practice question is part of Courseiva's free Google Cloud 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 PCD exam.
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