Quick Answer
The answer is to increase the instance class of the read replica. This is the correct solution because read replica lag occurs when the replica lacks sufficient compute and I/O capacity to apply the incoming changes from the primary’s binary log as fast as they are generated. By scaling up the replica’s instance class, you directly improve its CPU and memory resources, allowing it to process and apply write-ahead logs more efficiently, thereby reducing the replication lag. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how read replica lag is a resource bottleneck on the replica side, not the primary, and it often appears as a distractor where candidates mistakenly choose Multi-AZ or disabling binary logging. A common trap is assuming that upgrading the primary instance will fix replica lag, but the lag is caused by the replica’s inability to keep pace, not the primary’s write volume. Memory tip: “Lag is on the laggard” — the replica is the bottleneck, so scale the replica, not the source.
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 using Amazon RDS for MySQL and notices that read replicas are falling behind the primary. The primary instance is experiencing high write traffic. What is the best solution to reduce replica lag?
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.
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.
Increase the instance class of the read replica.
Larger instance class can apply changes faster.
Enable Multi-AZ on the primary instance.
Why wrong: Multi-AZ is for high availability, not replica lag.
Disable binary logging on the primary.
Why wrong: Binary logging is required for replication.
Move the read replica to the same AWS Region as the primary.
Why wrong: Read replicas can be in different regions, but same region reduces lag.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Increase the instance class of the read replica.
Option C is correct because increasing the replica instance class size improves its ability to apply changes. Option A is incorrect because Multi-AZ does not affect read replica lag. Option B is incorrect because read replicas cannot be in the same region. Option D is incorrect because disabling binary logging would break replication.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Increase the instance class of the read replica.
Why this is correct
Larger instance class can apply changes faster.
Clue confirmation
The clue words "best", "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Enable Multi-AZ on the primary instance.
Why it's wrong here
Multi-AZ is for high availability, not replica lag.
Disable binary logging on the primary.
Why it's wrong here
Binary logging is required for replication.
Move the read replica to the same AWS Region as the primary.
Why it's wrong here
Read replicas can be in different regions, but same region reduces lag.
Common exam traps
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
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
Identify which SAP-C02 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.
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FAQ
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — Read the scenario before looking for a memorised answer..
The correct answer is: Increase the instance class of the read replica. — Option C is correct because increasing the replica instance class size improves its ability to apply changes. Option A is incorrect because Multi-AZ does not affect read replica lag. Option B is incorrect because read replicas cannot be in the same region. Option D is incorrect because disabling binary logging would break replication.
Identify which SAP-C02 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.
Yes — watch for: "best", "primary". 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.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 20, 2026
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