The answer is that the BackupRetentionPeriod must be greater than 0 to enable automated backups, but since it is set to 7 in the CloudFormation template, the actual cause is likely an unsupported storage engine like MyISAM. Automated backups in RDS rely on the InnoDB storage engine for consistent snapshots; MyISAM does not support crash recovery or point-in-time restore, causing backups to fail silently even when the BackupRetentionPeriod is correctly configured. On the AWS Certified Database Specialty DBS-C01 exam, this tests your understanding that CloudFormation’s BackupRetentionPeriod parameter only enables the backup window—it does not guarantee backup success if the underlying engine is incompatible. A common trap is assuming a non-zero value alone solves the issue, but the exam often pairs this with engine-specific limitations. Memory tip: “InnoDB for backups, MyISAM for heart attacks”—always verify the engine when automated backups appear broken despite a valid retention period.
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 deploying a MySQL RDS instance using this CloudFormation template. After deployment, they notice that the database is not automatically backed up at the scheduled time. What is the most likely cause?
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.
The storage type gp2 does not support automated backups.
Why wrong: gp2 supports automated backups.
B
The PreferredBackupWindow is not defined, so backups are disabled.
Why wrong: The template defines a backup window.
C
MultiAZ is enabled, which disables automated backups.
Why wrong: MultiAZ does not disable backups; it is supported with backups.
D
The BackupRetentionPeriod must be greater than 0 to enable automated backups; however, it is set to 7, so this is not the issue. The actual cause might be that the DB instance is using a storage engine not supported for backups (e.g., MyISAM).
RDS automated backups require InnoDB; MyISAM tables cause backup failure.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The BackupRetentionPeriod must be greater than 0 to enable automated backups; however, it is set to 7, so this is not the issue. The actual cause might be that the DB instance is using a storage engine not supported for backups (e.g., MyISAM).
Option C is correct because to enable automated backups, the BackupRetentionPeriod must be greater than 0. In the snippet, it is set to 7, so backups should be enabled. However, automated backups are only supported for InnoDB storage engine; if the instance uses MyISAM, backups may fail. But the question asks for most likely cause; another common issue is that the backup window is too short or conflicts with maintenance, but the snippet shows valid windows. Option A is wrong because MultiAZ does not affect backups. Option B is wrong because storage type gp2 supports backups. Option D is wrong because the backup window is defined.
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 storage type gp2 does not support automated backups.
Why it's wrong here
gp2 supports automated backups.
✗
The PreferredBackupWindow is not defined, so backups are disabled.
Why it's wrong here
The template defines a backup window.
✗
MultiAZ is enabled, which disables automated backups.
Why it's wrong here
MultiAZ does not disable backups; it is supported with backups.
✓
The BackupRetentionPeriod must be greater than 0 to enable automated backups; however, it is set to 7, so this is not the issue. The actual cause might be that the DB instance is using a storage engine not supported for backups (e.g., MyISAM).
Why this is correct
RDS automated backups require InnoDB; MyISAM tables cause backup failure.
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.
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 BackupRetentionPeriod must be greater than 0 to enable automated backups; however, it is set to 7, so this is not the issue. The actual cause might be that the DB instance is using a storage engine not supported for backups (e.g., MyISAM). — Option C is correct because to enable automated backups, the BackupRetentionPeriod must be greater than 0. In the snippet, it is set to 7, so backups should be enabled. However, automated backups are only supported for InnoDB storage engine; if the instance uses MyISAM, backups may fail. But the question asks for most likely cause; another common issue is that the backup window is too short or conflicts with maintenance, but the snippet shows valid windows. Option A is wrong because MultiAZ does not affect backups. Option B is wrong because storage type gp2 supports backups. Option D is wrong because the backup window is defined.
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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