The answer is that the source table has a row exceeding MySQL’s 65,535-byte row size limit, which DMS cannot replicate to the target RDS instance. This error occurs because MySQL enforces a hard maximum row size regardless of storage engine, and DMS’s ongoing replication fails when it attempts to insert a row that surpasses this payload limit. On the AWS Certified Database Specialty DBS-C01 exam, this question tests your understanding of MySQL internals versus DMS configuration—a common trap is assuming a larger instance or default parameter group can fix row size issues, but neither changes the fundamental database limit. The key distinction is that the error originates from the source database’s row structure, not from DMS settings or target endpoint capacity. Memory tip: think “row size, not instance size”—the 65K limit is baked into MySQL’s engine, so always check source row lengths before blaming DMS.
DBS-C01 Deployment and Migration Practice Question
This DBS-C01 practice question tests your understanding of deployment and migration. 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 migrating a 500 GB MySQL database from an on-premises server to Amazon RDS for MySQL. The company uses AWS DMS with ongoing replication. The initial full load completes successfully, and the target RDS instance is in sync. However, after a few hours, the replication task fails with an error: 'Last Error: Error executing source loop; The table 'orders' has a row size larger than the maximum payload size of the target endpoint.' The target RDS instance is configured with db.r5.large and the default parameter group. The company has already verified that the table does not have any BLOB or TEXT columns. What is the MOST likely cause of this error?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The source table has a row that exceeds the MySQL row size limit.
RDS for MySQL has a maximum row size limit (65,535 bytes). DMS attempts to insert a row that exceeds this limit. Increasing the instance size does not change the row size limit. Using a different storage engine might help, but InnoDB is default. Enabling compression reduces row size but is not a direct solution for the DMS error.
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.
✗
The DMS task is using a low-memory instance.
Why it's wrong here
Memory does not affect row size limits.
✓
The source table has a row that exceeds the MySQL row size limit.
Why this is correct
MySQL enforces a row size limit; DMS cannot insert rows exceeding it.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The target RDS instance's max_allowed_packet parameter is set too low.
Why it's wrong here
max_allowed_packet affects network packet size, not row size.
✗
The target RDS instance does not have enough storage allocated.
Why it's wrong here
Storage allocation does not affect row size limits.
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 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 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.
Deployment and Migration — This question tests Deployment and Migration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The source table has a row that exceeds the MySQL row size limit. — RDS for MySQL has a maximum row size limit (65,535 bytes). DMS attempts to insert a row that exceeds this limit. Increasing the instance size does not change the row size limit. Using a different storage engine might help, but InnoDB is default. Enabling compression reduces row size but is not a direct solution for the DMS error.
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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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