The answer is that the TargetTablePrepMode is set to DROP_AND_CREATE, which causes indexes and keys to be missing after DMS migration. This is correct because when DMS uses DROP_AND_CREATE, it drops any existing target table and creates a new one using only the basic column definitions from the source—it does not replicate schema objects like primary keys, foreign keys, or indexes. On the AWS Certified Database Specialty DBS-C01 exam, this question tests your understanding of DMS’s schema replication limitations; a common trap is assuming DMS automatically migrates all schema elements, when in fact it focuses on data and basic table structure. To preserve constraints, you must pre-create them on the target or use TRUNCATE_BEFORE_LOAD instead. Memory tip: DROP_AND_CREATE drops everything but the data—think “DROP the schema, keep the columns only.”
DBS-C01 Deployment and Migration Practice Question
This DBS-C01 practice question tests your understanding of deployment and migration. 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.
A team is using AWS DMS to migrate a 3 TB Oracle database to Amazon Aurora PostgreSQL. They configured the task as shown. After the full load completes, they notice that the target tables have no indexes, primary keys, or foreign keys. 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.
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
✓
The TargetTablePrepMode is set to DROP_AND_CREATE, which creates tables without indexes or constraints.
When TargetTablePrepMode is set to DROP_AND_CREATE, AWS DMS drops the target table if it exists and then creates a new one using only the basic column definitions from the source. It does not migrate indexes, primary keys, or foreign keys because DMS is not designed to replicate schema objects beyond table structure and data. To preserve constraints and indexes, you must either pre-create them on the target or use a different prep mode like TRUNCATE_BEFORE_LOAD.
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 migration task did not include transformation rules to create indexes and constraints.
Why it's wrong here
Transformation rules can add metadata but are not required; the issue is with the default behavior of DROP_AND_CREATE.
✗
The table selection rule uses wildcards and excludes system tables, which also excludes index definitions.
Why it's wrong here
Table selection rules filter tables but do not affect index creation on included tables.
✓
The TargetTablePrepMode is set to DROP_AND_CREATE, which creates tables without indexes or constraints.
Why this is correct
DROP_AND_CREATE mode creates target tables with only the column definitions, not indexes or constraints.
Clue confirmation
The clue words "most likely", "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The task is using a full load without LOB support, which prevents index creation.
Why it's wrong here
LOB support does not affect index creation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume DMS automatically replicates all schema objects, including indexes and constraints, when in fact DMS only migrates table structure and data, leaving schema objects like indexes and foreign keys to be handled separately.
Detailed technical explanation
How to think about this question
Under the hood, DMS uses a minimal table creation statement (CREATE TABLE ... AS SELECT with no constraints) when TargetTablePrepMode is DROP_AND_CREATE. This is because DMS focuses on data movement and relies on the user to pre-provision schema objects like indexes and foreign keys on the target database. In real-world migrations, best practice is to create indexes and constraints after the full load completes to avoid performance degradation during data transfer, or to use AWS Schema Conversion Tool (SCT) to generate the target schema with all objects.
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.
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 TargetTablePrepMode is set to DROP_AND_CREATE, which creates tables without indexes or constraints. — When TargetTablePrepMode is set to DROP_AND_CREATE, AWS DMS drops the target table if it exists and then creates a new one using only the basic column definitions from the source. It does not migrate indexes, primary keys, or foreign keys because DMS is not designed to replicate schema objects beyond table structure and data. To preserve constraints and indexes, you must either pre-create them on the target or use a different prep mode like TRUNCATE_BEFORE_LOAD.
What should I do if I get this DBS-C01 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: "most likely", "primary". 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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