The answer is to upgrade the DB instance class to a larger size with more vCPUs, as this directly addresses both the high CPU usage and the resulting replica lag on the RDS PostgreSQL Multi-AZ deployment. When the primary instance is CPU-bound, it struggles to process write transactions and ship the WAL logs to the standby, causing replication lag to spike; a larger instance class provides the additional compute capacity needed to handle the workload and keep the standby synchronized. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding that Multi-AZ replication is synchronous and CPU-bound, so scaling vertically is the only way to reduce both CPU load and lag without changing application code—a common trap is confusing read replicas (which offload read traffic, not write load) with Multi-AZ standby. Remember the mnemonic: "CPU choked? Class up; replicas are for reads, not writes."
DBS-C01 Management and Operations Practice Question
This DBS-C01 practice question tests your understanding of management and operations. 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 runs a critical application on Amazon RDS for PostgreSQL with Multi-AZ. The database has a large table (over 500 GB) that is frequently updated. The operations team notices that the primary instance's CPU usage is consistently above 90%, and the replica lag between the primary and standby is increasing during peak hours. The application can tolerate a few seconds of downtime. The team needs to reduce CPU load and improve write performance without changing the application code. Which action should be taken?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Upgrade the DB instance class to a larger size with more vCPUs.
Option A is correct because upgrading to a larger instance class provides more CPU capacity, reducing the load and replication lag. Option B is wrong because read replicas are for read scaling, not for reducing write load on the primary. Option C is wrong because reducing replication lag is not achieved by changing backup retention. Option D is wrong because switching to asynchronous replication is not possible in Multi-AZ and would compromise durability.
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.
✓
Upgrade the DB instance class to a larger size with more vCPUs.
Why this is correct
More CPU capacity reduces the load on the primary and helps keep up with replication.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the backup retention period to reduce I/O during backups.
Why it's wrong here
Backup retention does not significantly affect CPU usage or replication lag.
✗
Modify the DB instance to use asynchronous replication instead of synchronous.
Why it's wrong here
Multi-AZ uses synchronous replication; switching to async is not supported for Multi-AZ and would risk data loss.
✗
Create a read replica in the same region and offload read queries to it.
Why it's wrong here
Read replicas reduce read load, but the issue is write-related CPU usage and replication lag.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 DBS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Management and Operations — This question tests Management and Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Upgrade the DB instance class to a larger size with more vCPUs. — Option A is correct because upgrading to a larger instance class provides more CPU capacity, reducing the load and replication lag. Option B is wrong because read replicas are for read scaling, not for reducing write load on the primary. Option C is wrong because reducing replication lag is not achieved by changing backup retention. Option D is wrong because switching to asynchronous replication is not possible in Multi-AZ and would compromise durability.
What should I do if I get this DBS-C01 question wrong?
Identify which DBS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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