DBS-C01 Deployment and Migration Practice Question
A company is migrating a 200 GB PostgreSQL database to Amazon Aurora PostgreSQL. They want to use the AWS DMS console to create a migration task. The source database is in a VPC and the target Aurora cluster is in the same VPC. The DMS replication instance is also in the same VPC. The source database is publicly accessible. What additional configuration is required to enable connectivity between DMS and the source database?
⚠ Common exam trap
Many candidates assume a publicly accessible source database requires public subnet placement or a VPC endpoint, but the key is that both resources are in the same VPC, so security group rules alone enable connectivity without exposing the database to the internet.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure the source database's security group to allow inbound traffic from the DMS replication instance's security group.
The source database is publicly accessible but resides in a VPC, and the DMS replication instance is in the same VPC. To allow the DMS replication instance to connect to the source database, the source database's security group must have an inbound rule that permits traffic on the database port (e.g., 5432 for PostgreSQL) from the DMS replication instance's security group. This ensures that only the replication instance can initiate the connection, maintaining security within the VPC.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Associate the DMS replication instance with a subnet group that includes public subnets.
Why it's wrong here
Subnet group is already set; the issue is about network connectivity.
- ✗
Place the source database in the same public subnet as the DMS replication instance.
Why it's wrong here
It's not necessary to change subnet; connectivity can be achieved via routing and security groups.
- ✗
Create a VPC endpoint for the source database service.
Why it's wrong here
VPC endpoints are for accessing AWS services, not on-premises or publicly accessible databases.
- ✓
Configure the source database's security group to allow inbound traffic from the DMS replication instance's security group.
Why this is correct
The security group must allow traffic from DMS to reach the database.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.