The answer is that the number of logical replication slots on the Aurora PostgreSQL instance exceeds the maximum supported. This is the most likely cause because AWS DMS relies on logical replication slots to capture and apply ongoing changes from the source Oracle database to the target Aurora PostgreSQL during ongoing replication. Each DMS task creates at least one replication slot on the target, and when the number of slots surpasses the Aurora PostgreSQL limit—typically one for Aurora Serverless v1 or a configurable limit for provisioned instances—the target instance can become unresponsive due to resource contention and slot management overhead. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how DMS interacts with Aurora’s replication architecture, often appearing as a trap where candidates blame network latency or source database load instead. A common memory tip is “one slot, one task, one limit”—if you exceed that, the target goes quiet.
SAP-C02 Practice Question: Accelerate Workload Migration and Modernization
This SAP-C02 practice question tests your understanding of accelerate workload migration and modernization. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 2 TB Oracle database to Amazon Aurora PostgreSQL. The database has frequent write operations and the migration must have minimal downtime. The team uses AWS DMS for ongoing replication. After the initial full load, the target Aurora instance becomes unresponsive during ongoing replication. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The number of logical replication slots on the Aurora PostgreSQL instance exceeds the maximum supported.
The most likely cause is that the number of logical replication slots on the Aurora PostgreSQL instance exceeds the maximum supported. AWS DMS uses logical replication slots to capture ongoing changes from the source Oracle database and apply them to the target Aurora PostgreSQL. Each DMS task creates at least one replication slot on the target. If the number of slots exceeds the Aurora PostgreSQL limit (typically 1 for Aurora Serverless v1 or a configurable limit for provisioned instances), the target instance can become unresponsive due to resource contention or slot management overhead.
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 configured to replicate DDL changes, which are not supported for Oracle to Aurora PostgreSQL.
Why it's wrong here
DDL replication is supported for some changes; this would not cause unresponsiveness.
✓
The number of logical replication slots on the Aurora PostgreSQL instance exceeds the maximum supported.
Why this is correct
Aurora PostgreSQL supports a limited number of replication slots; exceeding it causes failures.
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 DMS task is using full LOB mode, which is not supported with ongoing replication.
Why it's wrong here
Full LOB mode is supported for ongoing replication.
✗
The target Aurora instance's storage is full and cannot accept new writes.
Why it's wrong here
Aurora storage auto-scales; storage full is unlikely.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may incorrectly attribute the unresponsiveness to storage exhaustion (Option D) or unsupported LOB modes (Option C), overlooking the specific resource limitation of logical replication slots that is unique to Aurora PostgreSQL's managed replication architecture.
Detailed technical explanation
How to think about this question
Aurora PostgreSQL uses logical replication slots to track WAL (Write-Ahead Log) positions for each consumer. Each DMS task requires at least one slot, and the maximum number of slots is limited by the instance class and `max_replication_slots` parameter (default 10 for most Aurora PostgreSQL instances). Exceeding this limit can cause the PostgreSQL WAL sender processes to compete for resources, leading to high CPU or memory pressure that makes the instance unresponsive. In real-world scenarios, this often occurs when multiple DMS tasks are run concurrently or when tasks are restarted without cleaning up stale slots.
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.
Accelerate Workload Migration and Modernization — This question tests Accelerate Workload Migration and Modernization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The number of logical replication slots on the Aurora PostgreSQL instance exceeds the maximum supported. — The most likely cause is that the number of logical replication slots on the Aurora PostgreSQL instance exceeds the maximum supported. AWS DMS uses logical replication slots to capture ongoing changes from the source Oracle database and apply them to the target Aurora PostgreSQL. Each DMS task creates at least one replication slot on the target. If the number of slots exceeds the Aurora PostgreSQL limit (typically 1 for Aurora Serverless v1 or a configurable limit for provisioned instances), the target instance can become unresponsive due to resource contention or slot management overhead.
What should I do if I get this SAP-C02 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". 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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