The answer is to upgrade the DMS replication instance to a larger size to increase throughput. This directly addresses the bottleneck because a small replication instance lacks the CPU and memory needed to process the high volume of write transactions from the source Oracle database, especially during CDC replication. When the target Aurora instance struggles to keep up, the replication lag grows, and scaling the DMS instance vertically provides the additional compute capacity to handle the load and close the gap within the 2-day migration window. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of DMS performance tuning under real-world constraints like limited network bandwidth and heavy write workloads. A common trap is to focus on the source database or network, but the question explicitly states the replication instance is small, making it the clear bottleneck. Remember the memory tip: “Lag means lack of capacity—scale up the DMS, not the target.”
DBS-C01 Deployment and Migration Practice Question
This DBS-C01 practice question tests your understanding of deployment and migration. 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 3 TB on-premises Oracle database to Amazon Aurora PostgreSQL. The source database runs Oracle 12c on a Linux server with a 1 Gbps network connection to AWS via Direct Connect. The migration must have minimal downtime and be completed within a 2-day window. The database is heavily used during business hours (9 AM - 5 PM) and has low activity overnight. The company has a test environment on AWS already. The migration team plans to use AWS DMS with CDC for ongoing replication. They also plan to use AWS SCT for schema conversion. They start the migration on a Friday evening. On Saturday morning, the CDC replication lag is increasing, and the target Aurora instance is struggling to keep up. The team notices that the source database has a high number of write transactions even during the weekend, and the DMS replication instance is a small instance type. Which action should the team take to complete the migration on time?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Upgrade the DMS replication instance to a larger size to increase throughput.
Option B is correct because upgrading the DMS replication instance increases its capacity to handle high write volume. Option A is wrong because it doesn't address the bottleneck. Option C is wrong because it adds complexity and may not help. Option D is wrong because it doesn't solve the replication lag.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Reduce the number of tables being migrated to lower the load.
Why it's wrong here
Would not meet the requirement to migrate all data.
✓
Upgrade the DMS replication instance to a larger size to increase throughput.
Why this is correct
Larger instance can handle more write transactions.
Related concept
Standard ACLs match source addresses.
✗
Pause the migration and restart it on Monday during low activity.
Why it's wrong here
Would miss the 2-day window.
✗
Switch to use AWS Snowball to transfer data and bypass DMS.
Why it's wrong here
Snowball would take too long to set up and transfer.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DBS-C01 ACL questions on filtering logic and placement.
Deployment and Migration — This question tests Deployment and Migration — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Upgrade the DMS replication instance to a larger size to increase throughput. — Option B is correct because upgrading the DMS replication instance increases its capacity to handle high write volume. Option A is wrong because it doesn't address the bottleneck. Option C is wrong because it adds complexity and may not help. Option D is wrong because it doesn't solve the replication lag.
What should I do if I get this DBS-C01 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DBS-C01 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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This DBS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DBS-C01 exam.
Question Discussion
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