The correct choice is AWS Database Migration Service (DMS) with ongoing replication, because it enables a PostgreSQL migration to RDS with minimal downtime by using Change Data Capture (CDC) to continuously capture and apply live transactions from the on-premises source to the target RDS instance. This approach ensures that the target database stays synchronized during the migration window, allowing you to cut over with only a brief pause. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of migration strategies for large, continuously updated databases—a common trap is selecting a full-load-only DMS job or a native dump-and-restore tool like pg_dump, both of which require significant downtime. Remember the key distinction: if the question demands “minimal downtime” and “continuous updates,” your answer must include CDC. A useful memory tip is “CDC for zero-downtime DMS”—if you see ongoing replication or CDC in the options, that is the path to minimal disruption.
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 2 TB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL with minimal downtime. The database is continuously updated. Which migration strategy should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use AWS Database Migration Service (DMS) with ongoing replication from an on-premises source.
Option B (AWS DMS with ongoing replication) is correct because it supports minimal downtime by continuously replicating changes. Option A (native pg_dump/pg_restore) requires downtime. Option C (AWS Database Migration Service with full load only) does not replicate ongoing changes. Option D (SCT with Snowball) is for large-scale schema conversion, not minimal-downtime migration.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Use AWS Database Migration Service (DMS) with ongoing replication from an on-premises source.
Why this is correct
DMS with change data capture (CDC) allows continuous replication with minimal downtime.
Related concept
Static NAT maps one inside address to one outside address.
✗
Use AWS Schema Conversion Tool (SCT) and AWS Snowball to transfer data.
Why it's wrong here
SCT with Snowball is for schema conversion and large bulk transfers, not for minimal-downtime continuous replication.
✗
Use AWS Database Migration Service with a full load only, then cut over.
Why it's wrong here
Full load only does not capture ongoing changes; downtime would occur during cutover.
✗
Use pg_dump and pg_restore during a maintenance window.
Why it's wrong here
pg_dump/pg_restore requires downtime and cannot handle ongoing changes.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DBS-C01 NAT questions on configuration and troubleshooting.
Deployment and Migration — This question tests Deployment and Migration — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Use AWS Database Migration Service (DMS) with ongoing replication from an on-premises source. — Option B (AWS DMS with ongoing replication) is correct because it supports minimal downtime by continuously replicating changes. Option A (native pg_dump/pg_restore) requires downtime. Option C (AWS Database Migration Service with full load only) does not replicate ongoing changes. Option D (SCT with Snowball) is for large-scale schema conversion, not minimal-downtime migration.
What should I do if I get this DBS-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DBS-C01 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is migrating a 2 TB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL. The migration must have minimal downtime and support ongoing replication. Which AWS service should be used for the migration?
medium
A.AWS S3 Transfer Acceleration for direct database export
B.AWS Data Migration Service with AWS Glue
C.AWS Snowball Edge for offline data transfer
✓ D.AWS Database Migration Service (DMS) with change data capture
Why D: Option A is correct because AWS DMS supports ongoing replication from on-premises PostgreSQL to RDS for PostgreSQL using logical replication. Option B is wrong because S3 is for storage, not database migration. Option C is wrong because Snowball is for large data transfer offline, not minimal downtime replication. Option D is wrong because Database Migration Service is the correct name, not Data Migration Service.
Variation 2. A company is migrating a 1 TB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL. The migration must have minimal downtime. Which TWO steps should be taken to achieve this?
medium
✓ A.Configure AWS DMS with ongoing replication from the source to the target.
B.Use AWS SCT to convert the schema to Amazon Aurora.
✓ C.Use pglogical extension to replicate data from on-premises to RDS.
D.Take a full backup using pg_dump and import it into RDS during a maintenance window.
E.Create an RDS Read Replica of the on-premises database.
Why A: DMS with ongoing replication enables minimal downtime by continuously syncing changes. Using pglogical to replicate changes is another approach. Option B (importing a backup) causes downtime. Option D (creating a read replica) is not possible from on-premises. Option E (SCT for schema conversion) may be needed but not for minimal downtime.
Variation 3. A company is migrating a 2 TB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL. The database has a 4-hour downtime window. The company requires minimal data loss and wants to use AWS DMS. The on-premises network has a 100 Mbps internet connection. Which migration method should the company use?
medium
A.Use AWS Schema Conversion Tool (SCT) to migrate the data to Amazon RDS.
B.Use AWS DMS with a full load only, then stop the source database and resume applications.
C.Use pg_dump and pg_restore to export and import the database during the downtime window.
✓ D.Use AWS DMS with a full load and ongoing change data capture (CDC) replication.
Why D: Option B is correct because AWS DMS with a full load and ongoing CDC allows minimal downtime by continuously replicating changes. Option A is wrong because AWS DMS full load only does not capture ongoing changes, leading to data loss. Option C is wrong because pg_dump/pg_restore does not support CDC. Option D is wrong because AWS SCT is a schema conversion tool, not a data migration tool.
Last reviewed: Jun 20, 2026
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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.
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