CCNA Deployment and Migration Questions — Page 2 of 5

MCQhard

A company needs to migrate a 3 TB Amazon RDS for SQL Server database to Amazon RDS for PostgreSQL. The migration must be automated and repeatable with minimal manual intervention. Which combination of services should be used?

A.Use AWS SCT to convert the schema and export data to PostgreSQL-compatible format, then import.

B.Use AWS Schema Conversion Tool (SCT) to convert the schema, then use AWS DMS to migrate the data.

C.Use AWS DMS with native SQL Server CDC to migrate directly to PostgreSQL.

D.Use Microsoft Data Migration Assistant to assess and migrate to PostgreSQL.

AnswerB

SCT handles schema conversion, DMS handles data migration.

Why this answer

AWS Schema Conversion Tool (SCT) handles the schema conversion from SQL Server to PostgreSQL, which is necessary due to incompatible data types, stored procedures, and indexes. AWS Database Migration Service (DMS) then performs the continuous data migration with minimal downtime, supporting both full load and ongoing replication. This combination automates the migration process and makes it repeatable via AWS CloudFormation or DMS task templates.

Exam trap

The trap here is that candidates assume DMS alone can handle both schema conversion and data migration, but DMS does not perform schema transformation for heterogeneous migrations; schema conversion must be done separately with SCT before DMS can replicate the data.

How to eliminate wrong answers

Option A is wrong because AWS SCT can export data, but importing a 3 TB database manually is not automated or repeatable, and SCT alone does not provide ongoing replication to minimize downtime. Option C is wrong because AWS DMS with native SQL Server CDC can migrate data directly, but it does not convert the schema; PostgreSQL requires schema conversion from SQL Server, and DMS cannot handle incompatible data types or objects like sequences and stored procedures without prior schema transformation. Option D is wrong because Microsoft Data Migration Assistant is designed for SQL Server-to-SQL Server migrations (e.g., on-premises to Azure SQL Database) and does not support PostgreSQL as a target, nor does it integrate with AWS services for automation.

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MCQmedium

A company is migrating a 2 TB Oracle database to Amazon Aurora PostgreSQL using AWS SCT and DMS. After migration, the application reports that some queries are significantly slower than before. The database schema was converted automatically. What is the most likely cause?

A.The schema conversion did not create appropriate indexes

B.Aurora storage is slower than Oracle's storage

C.DMS introduced data type conversions that slow down queries

D.Aurora PostgreSQL does not support partitioning, causing full table scans

AnswerA

Indexes may not be migrated optimally, requiring manual tuning.

Why this answer

The most likely cause is that AWS Schema Conversion Tool (SCT) converted the Oracle schema to Aurora PostgreSQL but did not automatically create optimal indexes. Oracle and PostgreSQL use different query optimizers and index strategies; SCT focuses on structural compatibility, not performance tuning. Without manual review and addition of appropriate indexes (e.g., for foreign keys, composite columns, or partial indexes), PostgreSQL may resort to sequential scans on large tables, causing significant query slowdowns.

Exam trap

The trap here is that candidates assume schema conversion tools like SCT produce a fully optimized schema, when in fact they only ensure syntactic compatibility, leaving performance tuning—especially index creation—as a manual post-migration task.

How to eliminate wrong answers

Option B is wrong because Aurora storage is built on a distributed, SSD-backed volume that typically provides lower latency and higher throughput than traditional Oracle storage, not slower performance. Option C is wrong because DMS handles data type conversions during migration, but once data is in Aurora PostgreSQL, queries operate on native PostgreSQL types; any conversion overhead is negligible and does not cause persistent query slowness. Option D is wrong because Aurora PostgreSQL supports partitioning (table partitioning via declarative partitioning) and can use partition pruning to avoid full table scans; the absence of partitioning alone would not explain the slowdown.

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Multi-Selecthard

A company is migrating a 5 TB Oracle database to Amazon Aurora PostgreSQL. They have a 4-hour maintenance window weekly. Which THREE steps should be taken to minimize downtime? (Choose 3)

Select 3 answers

A.Create an Aurora read replica for testing.

B.Use AWS Snowball to transfer the initial data load.

C.Use AWS Direct Connect for network connectivity.

D.Use AWS DMS with change data capture (CDC).

E.Use AWS Schema Conversion Tool (SCT) to convert schema.

AnswersB, D, E

Speeds up initial load.

Why this answer

AWS Snowball provides a physical data transfer mechanism that avoids saturating the network for the initial 5 TB load, which could otherwise take days over typical internet connections. This allows the bulk data to be loaded into Amazon S3 and then into Aurora PostgreSQL before the cutover, while AWS DMS with CDC (Option D) captures ongoing changes to keep the target synchronized with the source during the migration window. Option E is correct because the AWS Schema Conversion Tool (SCT) is essential for converting the Oracle schema (including data types, stored procedures, and indexes) to Aurora PostgreSQL-compatible format before data migration begins, ensuring compatibility and reducing downtime during the final sync.

Exam trap

The trap here is that candidates may assume AWS Direct Connect (Option C) is always the best choice for large data transfers, but for a 5 TB initial load, Snowball is faster and more cost-effective than even a 10 Gbps Direct Connect link, which would still take over an hour for the transfer alone, not accounting for schema conversion and CDC setup.

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MCQmedium

A company is deploying a new Amazon Aurora MySQL database. The development team requires a separate database instance for testing that is a clone of the production database but does not require the same level of performance. What is the MOST cost-effective way to create this test database?

A.Use the Aurora cloning feature to create a clone of the production cluster

B.Create a new Aurora cluster from the latest snapshot of the production cluster

C.Create a read replica of the production cluster and promote it to a standalone cluster

D.Create a new Aurora cluster and use a smaller DB instance class

AnswerA

Aurora cloning is fast and space-efficient, ideal for test environments.

Why this answer

The Aurora cloning feature creates a copy of the production cluster that is both fast and storage-efficient, using copy-on-write technology. This clone can be created with a different (smaller) DB instance class than the source, meeting the requirement for lower performance at minimal cost, as no additional storage is provisioned until data is modified.

Exam trap

The trap here is that candidates often assume creating a new cluster from a snapshot (Option B) is the standard way to create a test database, overlooking the fact that Aurora cloning provides a faster and more cost-effective alternative by sharing storage pages until writes occur.

How to eliminate wrong answers

Option B is wrong because creating a new cluster from a snapshot incurs the full storage cost of the new cluster and takes longer to provision, making it less cost-effective than cloning. Option C is wrong because creating a read replica and promoting it to a standalone cluster still provisions a full replica with the same storage as the source, and the promotion process can cause data loss or inconsistency; it is not designed as a cost-effective cloning method. Option D is wrong because creating a new cluster from scratch (even with a smaller instance class) requires restoring data from a snapshot or exporting data, which incurs additional storage and compute costs, and does not leverage the zero-copy efficiency of Aurora cloning.

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MCQhard

A financial services company is migrating a 2 TB Oracle database to Amazon Aurora PostgreSQL. The database uses Oracle-specific features like hierarchical queries and stored procedures. The company wants to minimize manual code changes. Which service should be used to automate schema conversion?

A.AWS Database Migration Service (DMS) with full load and ongoing replication.

B.AWS Schema Conversion Tool (SCT).

C.AWS Storage Gateway to cache data on-premises and then sync to S3.

D.AWS Lambda to execute custom scripts for schema transformation.

AnswerB

SCT automates the conversion of Oracle schema objects to PostgreSQL-compatible format.

Why this answer

AWS Schema Conversion Tool (SCT) is specifically designed to convert database schemas from one engine to another, including Oracle to Amazon Aurora PostgreSQL. It automates the conversion of Oracle-specific features like hierarchical queries (CONNECT BY) and stored procedures into PostgreSQL-compatible syntax (e.g., recursive CTEs and PL/pgSQL), minimizing manual code changes. This makes SCT the correct choice for schema conversion, while AWS DMS handles data migration separately.

Exam trap

The trap here is that candidates often confuse AWS DMS (data migration) with schema conversion, assuming DMS can handle both data and schema transformation, but DMS only migrates data and requires a pre-converted target schema, which SCT provides.

How to eliminate wrong answers

Option A is wrong because AWS DMS focuses on data migration and ongoing replication, not schema conversion; it cannot translate Oracle-specific SQL syntax like hierarchical queries or stored procedures into PostgreSQL equivalents. Option C is wrong because AWS Storage Gateway is a hybrid storage service for caching and syncing files to S3, with no capability to convert or transform database schemas. Option D is wrong because AWS Lambda is a serverless compute service for running custom code, but it lacks built-in database schema conversion logic and would require extensive manual scripting to handle Oracle-to-PostgreSQL syntax translation, defeating the goal of minimizing manual code changes.

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MCQmedium

A user has the IAM policy shown in the exhibit. When attempting to create a DMS replication task, they receive an authorization error. What is the most likely missing permission?

A.ec2:DescribeSecurityGroups to allow network configuration

B.dms:CreateEndpoint permission

C.s3:PutObject for the S3 bucket

D.logs:CreateLogGroup to enable logging

AnswerB

The policy lacks permission to create endpoints, which are required for the replication task.

Why this answer

The user is attempting to create a DMS replication task, which requires the ability to create the underlying DMS resources. The error indicates a missing permission for the `dms:CreateEndpoint` action, as DMS replication tasks depend on source and target endpoints that must be created first. Without this permission, the API call to create the endpoint fails, resulting in an authorization error.

Exam trap

The trap here is that candidates often focus on permissions for the target service (like S3 or CloudWatch) or network-related actions, overlooking that the immediate authorization failure is due to missing the core DMS action required to create the endpoint itself.

How to eliminate wrong answers

Option A is wrong because `ec2:DescribeSecurityGroups` is used for network configuration but is not required to create a DMS replication task; DMS handles network settings via replication instances, not directly through security group descriptions. Option C is wrong because `s3:PutObject` is only needed if the DMS task writes to an S3 target, but the error occurs during task creation, not during data transfer, and the question does not specify S3 as a target. Option D is wrong because `logs:CreateLogGroup` is needed for enabling CloudWatch logging, but logging is optional and not a prerequisite for creating a replication task; the authorization error points to a missing core DMS permission, not a logging one.

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Multi-Selecthard

A company is planning to migrate a 1 TB MySQL database from on-premises to Amazon RDS for MySQL. The migration must have minimal downtime and support ongoing replication. Which THREE steps should the company include in the migration plan? (Choose THREE.)

Select 3 answers

A.Set up an AWS Direct Connect or VPN connection between on-premises and AWS.

B.Deploy an Amazon EC2 instance to act as a proxy for the DMS replication.

C.Create the target Amazon RDS for MySQL instance.

D.Use AWS DMS with ongoing replication from the on-premises MySQL database.

E.Install the AWS Schema Conversion Tool on the source server to convert the schema.

AnswersA, C, D

Network connectivity is required for DMS to access the source.

Why this answer

A stable, low-latency network connection (Direct Connect or VPN) is essential for AWS DMS to perform ongoing replication with minimal downtime. Without this, the replication can be interrupted by network issues, causing data loss or extended cutover windows.

Exam trap

The trap here is that candidates often assume an EC2 proxy is needed for DMS replication, but DMS replication instances handle connectivity directly, and the proxy is only used in specific scenarios like VPC peering across regions or complex network topologies.

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MCQeasy

A company wants to migrate an on-premises SQL Server database to Amazon RDS for SQL Server. They need to convert stored procedures and functions. Which AWS service should they use?

A.AWS CloudEndure Migration

B.AWS DMS

C.AWS SCT

D.AWS Snowball

AnswerC

SCT converts schema and code objects.

Why this answer

AWS SCT (Schema Conversion Tool) is the correct service because it specializes in converting database schemas, including stored procedures and functions, from one engine to another. For migrating on-premises SQL Server to Amazon RDS for SQL Server, SCT can analyze and convert the schema objects, handling syntax differences and compatibility issues automatically.

Exam trap

The trap here is that candidates confuse AWS DMS with schema conversion, but DMS only moves data and does not convert stored procedures or functions, which requires a separate schema conversion tool like AWS SCT.

How to eliminate wrong answers

Option A is wrong because AWS CloudEndure Migration is designed for block-level replication of entire servers (OS, applications, data) for lift-and-shift migrations, not for schema or code conversion. Option B is wrong because AWS DMS (Database Migration Service) handles data replication and ongoing synchronization, but it does not convert stored procedures, functions, or other schema objects—it moves data as-is. Option D is wrong because AWS Snowball is a physical data transfer device for large-scale data movement, not a tool for schema or code conversion.

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MCQhard

A database administrator runs the above CLI command. The output shows that 'mydb' is a read replica of 'mydb-source'. The administrator wants to promote 'mydb' to a standalone instance with no downtime. Which action should be taken?

A.Use the promote-read-replica CLI command.

B.Modify the DB instance to enable Multi-AZ, which automatically promotes it.

C.Create a snapshot of the read replica and restore it as a new DB instance.

D.Modify the DB instance class to a larger size to force promotion.

AnswerA

Promoting a read replica makes it a standalone instance without downtime.

Why this answer

The `promote-read-replica` CLI command is the correct action because it transitions the read replica from a replication slave to a standalone primary DB instance without requiring any downtime. During promotion, RDS stops replication and makes the replica writable, but the instance remains available throughout the process. This is the only method that achieves zero downtime promotion directly.

Exam trap

The trap here is that candidates may confuse promoting a read replica with other high-availability or backup operations, such as Multi-AZ or snapshot restore, which do not achieve the same zero-downtime promotion goal.

How to eliminate wrong answers

Option B is wrong because enabling Multi-AZ on a read replica does not promote it; Multi-AZ provides high availability by creating a standby in a different Availability Zone, but the replica remains a read replica until explicitly promoted. Option C is wrong because creating a snapshot and restoring it as a new instance incurs downtime during the snapshot and restore process, and it does not promote the existing read replica—it creates a separate, independent instance. Option D is wrong because modifying the DB instance class does not trigger promotion; changing the instance size is a scaling operation that does not alter the replication role of the read replica.

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MCQmedium

Refer to the exhibit. A developer runs the command against an RDS MySQL instance. The application team reports that the database is experiencing high read latency during peak hours. The database is not currently in Multi-AZ. What is the MOST cost-effective way to reduce read latency?

A.Enable Multi-AZ to distribute reads to the standby.

B.Upgrade the instance to db.r5.2xlarge.

C.Migrate to Aurora MySQL with a read replica.

D.Create a read replica in the same region.

AnswerD

Offloads read traffic; cost-effective.

Why this answer

Creating a read replica in the same region offloads read traffic from the primary RDS MySQL instance, reducing read latency during peak hours without incurring the cost of a larger instance or a full Aurora migration. Read replicas are asynchronous and can serve SELECT queries, providing a cost-effective scaling solution for read-heavy workloads.

Exam trap

The trap here is that candidates often confuse Multi-AZ with read scaling, assuming the standby can serve reads, but in RDS MySQL Multi-AZ, the standby is only used for failover and cannot accept connections.

How to eliminate wrong answers

Option A is wrong because Multi-AZ is designed for high availability and failover, not for distributing reads; the standby in a Multi-AZ deployment cannot serve read traffic. Option B is wrong because upgrading to a larger instance (db.r5.2xlarge) increases cost without addressing the root cause of read contention, and may not be the most cost-effective solution. Option C is wrong because migrating to Aurora MySQL with a read replica involves significant migration effort and cost, and is not the most cost-effective immediate fix for high read latency.

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MCQhard

A company is deploying a new web application on AWS. The application uses Amazon RDS for MySQL with a Multi-AZ deployment. The application team wants to reduce latency for read-heavy workloads. Which action should be taken?

A.Enable Multi-AZ on the existing RDS instance

B.Increase the instance size of the primary RDS instance

C.Add a read replica in the same Region

D.Switch from RDS to Amazon DynamoDB with DAX

AnswerC

Read replicas can handle read queries, reducing load on the primary and improving latency.

Why this answer

Adding a read replica in the same Region offloads read-heavy workloads from the primary RDS instance, reducing latency for read queries because replicas serve read traffic directly. Amazon RDS for MySQL read replicas use asynchronous replication and can be promoted to a primary instance if needed, making this the most effective and cost-efficient solution for read scaling.

Exam trap

The trap here is that candidates confuse Multi-AZ (which provides failover and high availability) with read replicas (which provide read scaling), leading them to incorrectly select Option A or B, thinking that adding Multi-AZ or a larger instance will reduce read latency.

How to eliminate wrong answers

Option A is wrong because Multi-AZ is already enabled per the question, and enabling it again does nothing; Multi-AZ provides high availability, not read scaling. Option B is wrong because increasing the instance size of the primary RDS instance may improve overall throughput but does not specifically reduce latency for read-heavy workloads, as the primary still handles all writes and reads, and scaling vertically is less efficient than horizontal read scaling. Option D is wrong because switching to DynamoDB with DAX is a complete database migration that introduces significant architectural changes, complexity, and potential application rewrites, which is unnecessary when a simple read replica can solve the latency issue.

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Multi-Selecthard

Which THREE considerations are important when deploying Amazon Aurora Global Database? (Choose 3.)

Select 3 answers

A.AWS DMS must be used to set up replication

B.Each secondary region can have up to 16 read replicas

C.Cross-region read replicas are created for each secondary region

D.Amazon S3 is used to store transaction logs

E.Replication is typically less than 1 second between regions

AnswersB, C, E

Correct. Each secondary region can have up to 16 read replicas.

Why this answer

Amazon Aurora Global Database allows each secondary region to have up to 16 read replicas, enabling low-latency global reads. Option C is correct because a secondary region gets its own Aurora cluster that functions as a cross-region read replica. Option E is correct because replication between the primary and secondary regions typically completes in less than one second, ensuring near-real-time data consistency.

Options A and D are incorrect: AWS DMS is not required for Aurora Global Database replication (it uses built-in storage-based replication), and transaction logs are stored in Aurora's storage layer, not in Amazon S3.

Exam trap

The trap here is that candidates often confuse Aurora Global Database with standard cross-region read replica setups (which use MySQL binary log replication) and incorrectly assume that cross-region read replicas are not created in each secondary region, or that AWS DMS or S3 is involved.

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MCQmedium

Refer to the exhibit. An IAM policy is attached to a user. The user tries to delete a database instance named 'prod-mydb' in us-east-1. What will happen?

A.The delete will be allowed because the Allow statement is broader.

B.The delete will fail with an error because the policy is invalid.

C.The delete will succeed only if the instance is tagged with 'Environment: prod'.

D.The delete will be denied because the Deny statement explicitly matches the resource.

AnswerD

Explicit Deny overrides Allow.

Why this answer

D is correct because IAM policy evaluation follows an explicit deny priority rule. Even though the Allow statement grants 'rds:DeleteDBInstance' on 'arn:aws:rds:us-east-1:*:db:*', the Deny statement explicitly matches the resource 'arn:aws:rds:us-east-1:123456789012:db:prod-mydb' and specifies 'rds:DeleteDBInstance'. Since an explicit deny overrides any allow, the delete operation will be denied.

Exam trap

The trap here is that candidates often assume a broader Allow statement will override a more specific Deny, but AWS IAM's explicit deny always wins, regardless of specificity or scope.

How to eliminate wrong answers

Option A is wrong because AWS IAM policy evaluation is not based on breadth; an explicit deny always overrides any allow, regardless of scope. Option B is wrong because the policy is syntactically valid—it contains valid Effect, Action, and Resource elements, and AWS will evaluate it without throwing an error. Option C is wrong because the Deny statement does not include a condition tag check; it unconditionally denies the specific resource, so tagging is irrelevant for this denial.

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MCQeasy

A company is deploying a new web application and needs a fully managed relational database with automatic failover and read replicas. Which AWS service should they choose?

A.Amazon DynamoDB

B.Amazon RDS for MySQL with Multi-AZ deployment

C.Amazon EC2 with self-managed MySQL

D.Amazon Redshift

AnswerB

RDS is fully managed, Multi-AZ provides automatic failover, and read replicas are supported.

Why this answer

Amazon RDS for MySQL with Multi-AZ deployment provides a fully managed relational database service that automatically provisions and maintains a synchronous standby replica in a different Availability Zone. In the event of a failure, Amazon RDS automatically fails over to the standby, ensuring high availability. Additionally, RDS for MySQL supports read replicas for offloading read traffic, which meets the requirement for both automatic failover and read replicas.

Exam trap

The trap here is that candidates often confuse DynamoDB's high availability and read replicas (DAX, global tables) with relational database requirements, or they assume that a self-managed database on EC2 can be 'fully managed' by using automation scripts, but the question explicitly requires a fully managed service.

How to eliminate wrong answers

Option A is wrong because Amazon DynamoDB is a NoSQL key-value and document database, not a relational database, and it does not support SQL joins or traditional relational schemas. Option C is wrong because Amazon EC2 with self-managed MySQL requires the company to manually configure and manage the database, including failover and read replicas, which contradicts the requirement for a 'fully managed' service. Option D is wrong because Amazon Redshift is a petabyte-scale data warehouse optimized for analytical queries, not a relational database for transactional web applications, and it does not provide automatic failover or read replicas in the same manner as RDS.

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Multi-Selectmedium

A company wants to migrate a 1 TB MySQL database to Amazon Aurora MySQL with minimal downtime. The database has a high write load. Which TWO options are valid approaches? (Choose two.)

Select 2 answers

A.Use AWS DMS with full load and ongoing replication.

B.Export to flat files, transfer via AWS Snowball, and import.

C.Perform a mysqldump and restore to Aurora.

D.Use MySQL native replication to replicate to Aurora MySQL.

E.Use AWS SCT to convert the schema and then use DMS.

AnswersA, D

DMS supports CDC for minimal downtime.

Why this answer

AWS DMS supports full load and ongoing change data capture (CDC) replication, which can migrate the 1 TB MySQL database to Aurora MySQL with minimal downtime by continuously applying changes from the source binary logs. This approach handles high write loads efficiently by using transactional replication to keep the target nearly synchronized until cutover.

Exam trap

The trap here is that candidates may overlook Option D as valid because they assume native replication is not supported between MySQL and Aurora MySQL, but Aurora MySQL fully supports MySQL native replication, making it a viable low-downtime migration approach alongside DMS.

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MCQeasy

A company wants to deploy a highly available Amazon RDS for MySQL database across two Availability Zones. Which feature should be enabled?

A.Read replicas in a different AZ

B.Automated backups with retention

C.Enhanced Monitoring

D.Multi-AZ deployment

AnswerD

Multi-AZ provides synchronous standby for automatic failover.

Why this answer

Multi-AZ deployment synchronously replicates data to a standby instance in a different Availability Zone, providing automatic failover in case of an AZ outage. This is the correct feature for achieving high availability across two Availability Zones, as it ensures minimal downtime without manual intervention.

Exam trap

The trap here is that candidates often confuse read replicas with Multi-AZ deployments, thinking that placing a read replica in a different AZ provides high availability, but read replicas are asynchronous and do not support automatic failover.

How to eliminate wrong answers

Option A is wrong because read replicas are designed for read scaling and do not provide automatic failover or synchronous replication; they are asynchronous and can have replication lag. Option B is wrong because automated backups are for point-in-time recovery and disaster recovery, not for real-time high availability or automatic failover across AZs. Option C is wrong because Enhanced Monitoring provides OS-level metrics for performance tuning, not high availability or failover capabilities.

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MCQeasy

A developer is configuring an RDS for PostgreSQL instance for a new application. The application requires automatic failover to a standby instance in a different Availability Zone. Which deployment option should be selected?

A.Deploy a Single-AZ instance with a read replica.

B.Deploy a Multi-AZ instance.

C.Deploy a Single-AZ instance and take frequent snapshots.

D.Deploy a Single-AZ instance with a cross-region read replica.

AnswerB

Multi-AZ provides automatic failover.

Why this answer

Multi-AZ deployment for RDS PostgreSQL automatically provisions and maintains a synchronous standby replica in a different Availability Zone. In the event of a failure or Availability Zone outage, Amazon RDS automatically fails over to the standby, providing high availability without manual intervention. This meets the requirement for automatic failover to a standby instance in a different AZ.

Exam trap

The trap here is that candidates often confuse read replicas (asynchronous, manual promotion) with Multi-AZ (synchronous, automatic failover), assuming any secondary instance provides automatic failover.

How to eliminate wrong answers

Option A is wrong because a Single-AZ instance with a read replica provides asynchronous replication and does not support automatic failover; the read replica must be manually promoted, which is not automatic. Option C is wrong because taking frequent snapshots provides point-in-time recovery but does not create a standby instance or enable automatic failover; recovery requires manual restoration. Option D is wrong because a cross-region read replica is asynchronous and intended for disaster recovery across regions, not for automatic failover within the same region; it also requires manual promotion.

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MCQhard

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size and has a high transaction rate. The migration must have minimal downtime and support ongoing replication. Which AWS service should be used for the migration?

A.AWS Schema Conversion Tool (AWS SCT)

B.AWS Database Migration Service (AWS DMS)

C.AWS Direct Connect

D.Amazon RDS Read Replica

AnswerB

AWS DMS supports ongoing replication from on-premises to RDS, enabling minimal downtime migrations.

Why this answer

AWS DMS is the correct service because it supports ongoing replication (change data capture) from an on-premises Oracle source to Amazon RDS for Oracle, enabling a migration with minimal downtime. It can handle a 2 TB database by using a full load followed by continuous replication of transactions, and it supports Oracle-specific features like supplemental logging and LogMiner for CDC.

Exam trap

The trap here is that candidates confuse AWS DMS with AWS SCT, thinking SCT handles data migration, but SCT only converts schema objects and does not perform any data transfer or replication.

How to eliminate wrong answers

Option A is wrong because AWS SCT is used for schema conversion (e.g., migrating from Oracle to Aurora PostgreSQL), not for data migration or ongoing replication; it does not move actual data. Option C is wrong because AWS Direct Connect provides a dedicated network connection for lower latency and higher bandwidth, but it is not a migration service—it does not perform data replication or CDC. Option D is wrong because Amazon RDS Read Replica is used for offloading read traffic or disaster recovery within AWS, not for migrating data from an on-premises database; it cannot connect to an external Oracle source.

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MCQeasy

After migrating a database to Amazon RDS, an application on an EC2 instance in the same VPC cannot connect. The command in the exhibit shows the endpoint. What is the most likely cause?

A.The EC2 instance is in a different VPC and needs a VPN connection.

B.The security group for the DB instance does not allow inbound traffic from the EC2 instance's security group.

C.The DB instance endpoint is incorrect.

D.The DB instance is not publicly accessible.

AnswerB

Security group rules control access; if not configured, connections are blocked.

Why this answer

The most likely cause is that the security group for the RDS DB instance does not have an inbound rule allowing traffic from the EC2 instance's security group on the database port (typically TCP 3306 for MySQL or 5432 for PostgreSQL). Even though both resources are in the same VPC, security groups act as virtual firewalls that must explicitly permit inbound connections from the source. The command output showing the endpoint confirms the DNS resolution works, so the issue is at the network access control layer.

Exam trap

The trap here is that candidates often assume that being in the same VPC guarantees connectivity, but AWS security groups are stateful and require explicit inbound rules, even for intra-VPC traffic, which is a core concept tested in the DBS-C01 exam.

How to eliminate wrong answers

Option A is wrong because the EC2 instance is stated to be in the same VPC, so a VPN connection is unnecessary and would not solve a connectivity issue within a single VPC. Option C is wrong because the exhibit shows the endpoint being used, and if the endpoint were incorrect, the command would likely fail with a 'Name or service not known' error rather than a connection timeout or refused error. Option D is wrong because public accessibility is irrelevant when both resources are in the same VPC; RDS instances in a VPC are accessible privately via their endpoint without needing public access enabled.

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MCQhard

A company is deploying a new application that requires a globally distributed database with low latency reads. They choose Amazon DynamoDB global tables. What is a key consideration for this deployment?

A.Writes are synchronously replicated to all regions.

B.Each replica can serve reads and writes independently.

C.The table class must be DynamoDB Standard-Infrequent Access.

D.Global tables support strongly consistent reads from any region.

AnswerB

Global tables are multi-master; each region can handle both reads and writes.

Why this answer

Amazon DynamoDB global tables use a multi-master, active-active replication model. This means each replica region can independently serve both reads and writes, with eventual consistency across regions. This design enables low-latency local reads and writes for globally distributed applications, as each region operates autonomously.

Exam trap

The trap here is confusing asynchronous multi-master replication with synchronous replication, leading candidates to incorrectly assume that global tables provide strong consistency across regions or that writes are synchronous.

How to eliminate wrong answers

Option A is wrong because writes in DynamoDB global tables are replicated asynchronously, not synchronously; synchronous replication would introduce cross-region latency and conflict. Option C is wrong because global tables support any DynamoDB table class (Standard, Standard-IA, etc.), and Standard-Infrequent Access is not a requirement. Option D is wrong because global tables only support eventually consistent reads from any replica region; strongly consistent reads are only available from the region where the write was performed, as they require a quorum read from the local replica.

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Multi-Selectmedium

Which TWO of the following are valid considerations when migrating an on-premises Oracle database to Amazon RDS for Oracle using AWS DMS? (Select TWO.)

Select 2 answers

A.DMS automatically converts Oracle stored procedures to RDS for Oracle compatible code.

B.DMS can continue to replicate changes after the full load is complete until the cutover.

C.DMS automatically converts partitioned tables to non-partitioned tables.

D.DMS can migrate directly to Amazon RDS Custom for Oracle without any configuration changes.

E.DMS can perform ongoing replication to minimize downtime during migration.

AnswersB, E

DMS supports ongoing replication for near-zero downtime.

Why this answer

AWS DMS supports ongoing replication (change data capture, CDC) after the full load completes, allowing you to keep the target database synchronized with the source until you perform the cutover. This minimizes downtime because you can replicate ongoing changes from the on-premises Oracle database to Amazon RDS for Oracle, then stop all applications and switch over with only a brief interruption.

Exam trap

AWS often tests the misconception that AWS DMS can automatically convert database code (like stored procedures) or that it can handle all schema transformations without additional tools, but in reality DMS focuses on data migration and ongoing replication, while schema and code conversion requires AWS Schema Conversion Tool (SCT).

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Multi-Selecthard

A company is migrating a 1 TB SQL Server database to Amazon RDS for SQL Server. The migration requires minimal downtime and must support ongoing changes. Which TWO AWS services should be used together to achieve this? (Choose two.)

Select 2 answers

A.AWS Schema Conversion Tool (AWS SCT) and AWS Snowball

B.AWS Database Migration Service (AWS DMS) and AWS Direct Connect

C.AWS Database Migration Service (AWS DMS) and AWS Lambda

D.AWS Database Migration Service (AWS DMS) and AWS Schema Conversion Tool (AWS SCT)

E.AWS Database Migration Service (AWS DMS) and AWS Snowball

AnswersD, E

DMS handles ongoing replication; SCT helps with schema conversion for compatibility.

Why this answer

To migrate a 1 TB SQL Server database to Amazon RDS for SQL Server with minimal downtime and ongoing changes, two services are needed. AWS DMS provides continuous replication (change data capture) to keep the target synchronized. For the initial bulk transfer of 1 TB, AWS Snowball can physically move the data offline, reducing network load and accelerating the initial load; DMS then takes over for ongoing changes.

Alternatively, DMS can be combined with AWS SCT for schema conversion and optimization, which is useful even when migrating to the same engine. Thus, both options D (DMS+SCT) and E (DMS+Snowball) are correct because they represent valid combinations for achieving minimal-downtime migration with ongoing changes.

Exam trap

Candidates may think only DMS is needed, but for large datasets like 1 TB, combining DMS with Snowball (offline initial load) enables faster migration while still supporting ongoing replication. Alternatively, pairing DMS with SCT addresses schema conversion. Both combinations are valid, and candidates must recognize that two services are required for this scenario.

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MCQmedium

A company wants to migrate an on-premises MySQL database to Amazon RDS for MySQL with minimal downtime. The database is 500 GB and has moderate write activity. Which approach is MOST suitable?

A.Use AWS Database Migration Service (DMS) with a full load and ongoing replication.

B.Use mysqldump to export the database, then import into RDS.

C.Use AWS Server Migration Service (SMS) to migrate the database server.

D.Create a read replica of the on-premises database and promote it to RDS.

AnswerA

DMS supports ongoing replication to minimize downtime.

Why this answer

AWS DMS with full load and ongoing replication is the most suitable approach because it supports continuous change data capture (CDC) from the on-premises MySQL source to the Amazon RDS target, enabling minimal downtime. The full load transfers the initial 500 GB dataset, while ongoing replication applies incremental changes until cutover, meeting the requirement for minimal downtime with moderate write activity.

Exam trap

The trap here is that candidates often confuse AWS Server Migration Service (SMS) as a database migration tool or assume that creating a read replica from an on-premises database is possible, when in fact read replicas are an Amazon RDS-specific feature that requires the source to be an RDS instance, not an on-premises server.

How to eliminate wrong answers

Option B is wrong because mysqldump performs a logical export that locks tables during the dump, causing significant downtime for a 500 GB database with moderate write activity, and it cannot provide ongoing replication to minimize downtime. Option C is wrong because AWS Server Migration Service (SMS) is designed for migrating virtual machines (VMs) as server images, not for database-level migration, and it does not support MySQL replication or CDC. Option D is wrong because creating a read replica of an on-premises database is not natively supported by MySQL; read replicas are an Amazon RDS feature for replicating within AWS, and promoting a read replica to a standalone instance does not apply to on-premises sources.

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MCQmedium

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database uses Oracle Data Pump for export/import. The migration must be completed within a short maintenance window. Which migration approach should they use?

A.Use AWS Snowball to transfer the database files to AWS and then restore to RDS.

B.Use AWS Database Migration Service with full load and change data capture (CDC).

C.Use Oracle Data Pump to export the database and import into RDS.

D.Use AWS Schema Conversion Tool (SCT) to convert the schema and then use DMS for data migration.

AnswerB

AWS DMS with full load and CDC satisfies the short maintenance window constraint by performing an initial full copy of the Oracle database while simultaneously capturing ongoing changes via redo log mining. This allows the target RDS for Oracle instance to stay synchronised with the source during the migration, so cutover can occur with minimal downtime rather than requiring a single extended export/import window.

Why this answer

AWS Database Migration Service (DMS) with full load and change data capture (CDC) is the correct approach because it minimizes downtime by performing an initial full load of the Oracle database and then continuously replicating ongoing changes until the cutover, allowing the migration to complete within a short maintenance window. Unlike Oracle Data Pump, which requires the source database to be offline during export/import, DMS with CDC keeps the source operational and only requires a brief outage at final cutover.

Exam trap

The trap here is that candidates assume Oracle Data Pump (Option C) is the fastest because it's a native Oracle tool, but they overlook that it requires the source database to be offline during export, which violates the short maintenance window constraint, whereas DMS with CDC allows near-zero downtime.

How to eliminate wrong answers

Option A is wrong because AWS Snowball is designed for large-scale offline data transfer of flat files, not for direct database migration to RDS; it would require additional steps to restore from files, increasing complexity and time, and does not support CDC for minimal downtime. Option C is wrong because Oracle Data Pump export/import requires the source database to be offline or in restricted mode during the export, and the import into RDS also takes significant time, making it unsuitable for a short maintenance window. Option D is wrong because AWS Schema Conversion Tool (SCT) is used for heterogeneous migrations (e.g., Oracle to Aurora or PostgreSQL), not for homogeneous Oracle-to-Oracle migrations; using SCT here is unnecessary and adds complexity without benefit.

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100

MCQhard

A database administrator runs the command shown in the exhibit to create a read replica in us-west-2 from a source DB instance in us-east-1. The command fails. What is the most likely cause?

A.The source DB instance does not have backup retention enabled.

B.The source DB instance is not publicly accessible.

C.The replica instance class db.r5.large is not available in us-west-2.

D.The replica must use the same DB instance class as the source.

AnswerA

Cross-region read replicas require automated backups enabled on the source.

Why this answer

The command fails because creating a cross-Region read replica requires the source DB instance to have automated backups enabled (backup retention period > 0). Without backups, Amazon RDS cannot generate the necessary transaction logs to replicate data to the replica in us-west-2. This is a prerequisite for any read replica creation, whether in the same Region or across Regions.

Exam trap

The trap here is that candidates often assume the failure is due to instance class availability or public accessibility, overlooking the mandatory backup retention requirement for read replica creation.

How to eliminate wrong answers

Option B is wrong because public accessibility of the source DB instance is not required for cross-Region read replica creation; RDS uses internal network paths and VPC peering or VPN connections for replication, not public internet. Option C is wrong because if the db.r5.large instance class were unavailable in us-west-2, the error would be an instance class availability issue, but the command would still attempt validation and fail with a specific 'instance class not supported' error, not a generic failure. Option D is wrong because the replica can use a different DB instance class than the source; RDS allows scaling the replica independently as long as the chosen class is compatible with the engine and Region.

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101

MCQeasy

A company is migrating an on-premises MySQL database to Amazon RDS for MySQL. The database is 500 GB in size and has a 24-hour maintenance window. Which AWS service or tool should be used for the initial data transfer with minimal downtime?

A.Amazon S3 with AWS Glue

B.AWS Snowball Edge

C.AWS Database Migration Service (DMS)

D.mysqldump and restore to RDS

AnswerC

DMS supports ongoing replication from on-premises to RDS, minimizing downtime.

Why this answer

AWS Database Migration Service (DMS) is the correct choice because it supports ongoing replication from a source MySQL database to Amazon RDS for MySQL, allowing you to perform a full load followed by continuous change data capture (CDC) to minimize downtime. With a 500 GB database and a 24-hour maintenance window, DMS can complete the initial load and then keep the target in sync until you cut over, achieving near-zero downtime.

Exam trap

The trap here is that candidates often choose mysqldump (Option D) because it is familiar and free, but they overlook that it requires locking tables or stopping writes, which violates the 'minimal downtime' requirement for a 24-hour maintenance window.

How to eliminate wrong answers

Option A is wrong because Amazon S3 with AWS Glue is designed for ETL and data transformation, not for direct database migration with minimal downtime; Glue cannot perform live CDC from MySQL to RDS. Option B is wrong because AWS Snowball Edge is a physical data transfer device intended for large datasets (typically >10 TB) over slow networks, and for a 500 GB database, the overhead of shipping and copying data would exceed the 24-hour window and cannot achieve minimal downtime. Option D is wrong because mysqldump and restore is a logical backup method that requires taking the source database offline or locking tables during the dump, causing significant downtime, and it does not support ongoing replication to keep the target in sync.

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102

MCQhard

A company is deploying a new Amazon RDS for SQL Server DB instance with Multi-AZ. The database will be used by a critical application that requires minimal downtime during failover. The application uses a single connection string with the CNAME of the RDS endpoint. During a recent failover test, the application experienced a 3-minute timeout. The DBA wants to reduce the failover time. The current RDS instance is db.r5.large with 100 GB gp2 storage. The application is hosted on EC2 in the same VPC. Which change would MOST effectively reduce the failover time?

A.Change the storage to Provisioned IOPS (io1)

B.Change the instance type to db.r5.xlarge

C.Configure the application to use a low TTL for DNS lookups and implement connection retries

D.Use a read replica with automatic failover

AnswerC

Low TTL ensures the DNS record is refreshed quickly, reducing failover time.

Why this answer

The most effective because the 3-minute timeout during failover is likely due to DNS caching on the application side. By configuring the application to use a low TTL (e.g., 5 seconds) for DNS lookups and implementing connection retries with exponential backoff, the application can quickly resolve the new RDS endpoint's IP address after failover and re-establish connectivity promptly. Option A is incorrect because changing to Provisioned IOPS (io1) improves storage performance but does not reduce DNS-related failover time.

Option B is incorrect because increasing the instance size does not directly impact failover duration. Option D is incorrect because Multi-AZ already provides automatic failover; a read replica with manual promotion would not reduce failover time and would require additional management.

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103

MCQhard

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?

A.Reduce the number of tables being migrated to lower the load.

B.Upgrade the DMS replication instance to a larger size to increase throughput.

C.Pause the migration and restart it on Monday during low activity.

D.Switch to use AWS Snowball to transfer data and bypass DMS.

AnswerB

Larger instance can handle more write transactions.

Why this answer

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.

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104

MCQhard

A company is deploying a multi-region application with Amazon Aurora Global Database. They need to ensure that the secondary region can be promoted to primary with minimal data loss in the event of a regional failure. Which configuration should they use?

A.Deploy Amazon Aurora Serverless with cross-Region replication.

B.Deploy Amazon Aurora Global Database with one primary Region and up to five secondary Regions.

C.Deploy Amazon RDS for MySQL with cross-Region read replicas.

D.Deploy Amazon RDS for PostgreSQL with Multi-AZ and cross-Region snapshot copy.

AnswerB

Aurora Global Database provides low-latency reads and managed failover with minimal data loss.

Why this answer

Amazon Aurora Global Database is designed for low-latency cross-Region replication and provides a managed failover capability that promotes a secondary Region to primary with a Recovery Point Objective (RPO) of typically less than 1 second. This configuration meets the requirement of minimal data loss during a regional failure because replication is done at the storage layer, not through asynchronous binlog replication, ensuring near-zero lag.

Exam trap

The trap here is that candidates often confuse cross-Region read replicas (which are asynchronous and can lose data) with Aurora Global Database's storage-level replication, which provides near-zero RPO and automated promotion capabilities.

How to eliminate wrong answers

Option A is wrong because Amazon Aurora Serverless does not support cross-Region replication or Global Database; it is designed for intermittent workloads and scales automatically within a single Region. Option C is wrong because Amazon RDS for MySQL cross-Region read replicas use asynchronous replication with potentially higher lag and no automated promotion to primary, leading to greater data loss. Option D is wrong because Amazon RDS for PostgreSQL Multi-AZ provides high availability within a single Region, and cross-Region snapshot copy is not a replication mechanism; it requires manual restore and cannot achieve minimal data loss during failover.

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105

MCQeasy

A company has a 100 GB MySQL database on an EC2 instance. They want to migrate to Amazon RDS for MySQL with minimal downtime. They have set up replication from the source to the target using MySQL native replication. After enabling replication, the 'Seconds_Behind_Master' value is increasing. The source database is write-heavy. What should the team do to reduce replication lag?

A.Tune the source database to reduce write load.

B.Enable Multi-AZ on the RDS instance.

C.Increase the RDS instance size to a larger instance class.

D.Switch to AWS DMS for migration.

AnswerC

Increasing the RDS instance size gives more CPU and memory resources to the database, enabling it to apply replication changes faster and reduce the 'Seconds_Behind_Master' value.

Why this answer

The replication lag is increasing because the RDS instance is not powerful enough to apply changes from the write-heavy source as fast as they arrive. Increasing the RDS instance class (option C) provides more CPU and memory resources, allowing the replica to apply transactions more quickly and reduce lag. Option A (tuning the source) might help but is not the most direct solution if the target is the bottleneck.

Option B (Multi-AZ) improves availability, not replication performance. Option D (AWS DMS) is an alternative migration tool but does not directly address lag in an existing native replication setup.

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106

MCQhard

A company is running a production PostgreSQL database on an EC2 instance (db.m5.xlarge) with 500 GB of gp2 EBS storage. The database is used by a customer-facing application that requires low latency. The company plans to migrate this database to Amazon RDS for PostgreSQL with minimal downtime. The current database has a high write load with frequent updates and deletes, and the table sizes are growing. The company also wants to enable Multi-AZ for high availability and use read replicas for reporting workloads. During migration planning, they discover that the source database has several large unlogged tables and uses custom PostgreSQL extensions that are not available in RDS. Which migration strategy should the company use to minimize downtime and meet all requirements?

A.Use AWS DMS with ongoing replication, convert unlogged tables to logged tables, and migrate custom extensions using AWS SCT.

B.Use pg_dump to export the database and pg_restore to import into RDS, then set up read replicas.

C.Copy the database files to Amazon S3, then use the rdsadmin.rdsadmin_restore_from_s3 procedure to restore to RDS.

D.Set up PostgreSQL streaming replication from the EC2 instance to an RDS read replica, then promote the replica.

AnswerA

DMS can handle unlogged tables by replicating data as regular tables, and SCT can suggest alternatives for unsupported extensions.

Why this answer

AWS DMS with ongoing replication allows near-zero downtime by continuously replicating changes from the source to the target RDS instance. DMS can handle unlogged tables by converting them to logged tables during migration, as DMS requires logical replication which relies on write-ahead logs. AWS SCT can help assess and convert custom PostgreSQL extensions to RDS-compatible equivalents or suggest alternatives.

Option B (pg_dump/pg_restore) is an offline approach that would cause significant downtime, which does not meet the minimal downtime requirement. Option C (copy to S3 then restore) is not a supported migration method for PostgreSQL to RDS. Option D (streaming replication) is not feasible because RDS does not accept direct streaming replication from an external source, and unlogged tables cannot be replicated via streaming.

Therefore, A is the best strategy.

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107

MCQeasy

A company wants to deploy an Amazon RDS for MySQL database for a new application. The database must be highly available with automatic failover. Which configuration should they choose?

A.Deploy a single-AZ instance with automated backups

B.Deploy a cross-region replica

C.Deploy a single-AZ instance with a read replica

D.Deploy a Multi-AZ instance with a standby replica

AnswerD

Multi-AZ provides automatic failover to the standby.

Why this answer

A Multi-AZ deployment for Amazon RDS automatically provisions and maintains a synchronous standby replica in a different Availability Zone. In the event of a failure, Amazon RDS automatically fails over to the standby, providing high availability without manual intervention. This configuration meets the requirement for automatic failover and high availability.

Exam trap

The trap here is that candidates often confuse read replicas with Multi-AZ standby replicas, assuming that a read replica can provide automatic failover, but read replicas require manual promotion and may have data loss due to asynchronous replication.

How to eliminate wrong answers

Option A is wrong because a single-AZ instance with automated backups provides point-in-time recovery but does not offer automatic failover; if the instance fails, downtime occurs until a new instance is restored from backups. Option B is wrong because a cross-region replica is an asynchronous read replica used for disaster recovery or read scaling, not for automatic failover within the same region; it requires manual promotion to become the primary. Option C is wrong because a single-AZ instance with a read replica provides read scaling and can be manually promoted for failover, but it does not provide automatic failover; the read replica is asynchronous and may have replication lag.

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108

MCQmedium

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?

A.Associate the DMS replication instance with a subnet group that includes public subnets.

B.Place the source database in the same public subnet as the DMS replication instance.

C.Create a VPC endpoint for the source database service.

D.Configure the source database's security group to allow inbound traffic from the DMS replication instance's security group.

AnswerD

The security group must allow traffic from DMS to reach the database.

Why this answer

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.

Exam trap

The trap here is that 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.

How to eliminate wrong answers

Option A is wrong because associating the DMS replication instance with a subnet group that includes public subnets is unnecessary and irrelevant; the replication instance is already in the same VPC as the source and target, and connectivity is controlled by security groups, not subnet type. Option B is wrong because placing the source database in the same public subnet as the DMS replication instance is not required and may violate security best practices; the source database can remain in its current subnet as long as security group rules allow traffic. Option C is wrong because a VPC endpoint is used to privately connect to AWS services (e.g., S3, DynamoDB) without traversing the internet, but the source database is a self-managed PostgreSQL instance, not an AWS service, so a VPC endpoint does not apply.

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109

MCQmedium

A company is deploying a new multi-AZ Amazon RDS for PostgreSQL database. The security team requires that all traffic to the database be encrypted in transit. Which configuration ensures this?

A.Use a customer master key (CMK) for RDS

B.Enable SSL/TLS and require client connections to use SSL

C.Place the RDS instance in a public subnet

D.Enable encryption at rest using AWS KMS

AnswerB

SSL/TLS encrypts data in transit.

Why this answer

Enabling SSL/TLS on the RDS instance and requiring client connections to use SSL ensures that all data transmitted between clients and the database is encrypted in transit. This is achieved by setting the rds.force_ssl parameter to 1 in the DB parameter group, which enforces SSL/TLS for all connections, meeting the security team's requirement for encryption in transit.

Exam trap

The trap here is confusing encryption at rest (KMS, CMK) with encryption in transit (SSL/TLS), leading candidates to select options that secure data on disk but not during network transmission.

How to eliminate wrong answers

Option A is wrong because using a customer master key (CMK) for RDS encrypts data at rest, not in transit; CMKs are used with AWS KMS for storage encryption, not for network traffic. Option C is wrong because placing the RDS instance in a public subnet exposes it to the internet, which does not inherently encrypt traffic and violates security best practices; encryption in transit requires SSL/TLS, not subnet placement. Option D is wrong because enabling encryption at rest using AWS KMS protects data stored on disk, not data transmitted over the network; it does not address encryption in transit.

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110

MCQmedium

Refer to the exhibit. A company is creating an Aurora MySQL cluster using the AWS CLI. The command fails with an error. The company has a default KMS key but the command specifies a customer-managed KMS key. What is the most likely cause of the failure?

A.The IAM user does not have permission to use the specified KMS key

B.The --kms-key-id parameter is not supported for aurora-mysql engine

C.The KMS key does not exist

D.The KMS key is in a different region

AnswerA

Permission to use the KMS key is required.

Why this answer

The most likely cause of the failure is that the IAM user does not have the required permissions to use the specified customer-managed KMS key. When you specify a KMS key in the `--kms-key-id` parameter for an Aurora MySQL cluster, the IAM user must have `kms:CreateGrant`, `kms:Decrypt`, and `kms:Encrypt` permissions on that key. If the user lacks these permissions, the command fails even if the key exists and is in the correct region.

Exam trap

The trap here is that candidates often assume the error is due to the key not existing or being in a different region, but the most common failure is an IAM permissions issue on the KMS key, especially when a customer-managed key is specified instead of the default AWS managed key.

How to eliminate wrong answers

Option B is wrong because the `--kms-key-id` parameter is fully supported for the `aurora-mysql` engine; Aurora MySQL supports encryption at rest using KMS keys. Option C is wrong because the question states the company has a default KMS key, and the command specifies a customer-managed KMS key, but the error is not about the key's existence—it's about permissions; if the key did not exist, the error would be 'Key not found' or similar. Option D is wrong because if the KMS key were in a different region, the CLI would return a 'Region mismatch' or 'InvalidKeyId' error, but the question does not indicate a cross-region scenario, and the most common cause in single-region setups is missing IAM permissions.

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111

MCQhard

A financial services company is migrating a 10 TB Oracle data warehouse to Amazon Redshift. The source database uses a combination of partitioned tables, indexes, and materialized views. The migration team plans to use AWS SCT and DMS. Which approach should the team take to optimize query performance after migration?

A.Create indexes on frequently queried columns

B.Recreate all materialized views using standard views

C.Define appropriate distribution keys and sort keys

D.Partition tables by date using the PARTITION BY clause

AnswerC

These are the primary performance optimization mechanisms in Redshift.

Why this answer

Amazon Redshift is a columnar data warehouse that does not support traditional indexes or the PARTITION BY clause used in Oracle. Instead, query performance in Redshift is optimized by defining appropriate distribution keys (to minimize data shuffling across nodes) and sort keys (to enable zone maps and reduce the amount of data scanned). This approach directly addresses the performance needs of the migrated 10 TB data warehouse.

Exam trap

The trap here is that candidates familiar with traditional RDBMS concepts (indexes, table partitioning) assume they apply directly to Redshift, but Redshift uses a fundamentally different architecture where distribution and sort keys are the primary performance levers.

How to eliminate wrong answers

Option A is wrong because Amazon Redshift does not use traditional B-tree or bitmap indexes; it relies on sort keys and zone maps for data skipping. Option B is wrong because materialized views in Redshift can improve performance by pre-computing and storing results, whereas standard views execute the underlying query each time, often leading to slower performance. Option D is wrong because Redshift does not support the Oracle-style PARTITION BY clause; it uses distribution keys and sort keys to manage data layout across nodes.

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112

Multi-Selecteasy

Which TWO AWS services can be used to migrate an on-premises SQL Server database to Amazon RDS for SQL Server?

Select 2 answers

A.AWS DataSync

B.AWS DMS

C.Native SQL Server backup to S3 and restore to RDS

D.AWS Storage Gateway

E.AWS DynamoDB

AnswersB, C

DMS supports SQL Server as source and target.

Why this answer

AWS DMS (Database Migration Service) is correct because it is purpose-built for migrating databases to AWS with minimal downtime, supporting homogeneous migrations like SQL Server to Amazon RDS for SQL Server. It uses change data capture (CDC) to replicate ongoing changes, enabling near-zero downtime migrations. Native SQL Server backup to S3 and restore to RDS is also correct because SQL Server's native backup/restore mechanism can be used to take a full backup, upload it to Amazon S3, and then restore it directly onto an RDS for SQL Server instance, which is a supported and common offline migration method.

Exam trap

The trap here is that candidates often assume only AWS DMS is valid for database migrations, overlooking the fact that native SQL Server backup/restore to S3 is a fully supported and often simpler offline migration method for SQL Server to RDS.

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113

MCQeasy

A company is migrating an on-premises MongoDB database to Amazon DocumentDB. The migration must be online with minimal downtime. Which AWS service should be used?

A.AWS DataSync

B.AWS DMS

C.AWS S3

D.AWS Snowball Edge

AnswerB

DMS supports MongoDB to DocumentDB with CDC for minimal downtime.

Why this answer

AWS Database Migration Service (DMS) is the correct choice because it supports ongoing replication (change data capture) from MongoDB to Amazon DocumentDB, enabling an online migration with minimal downtime. DMS can perform a full load of existing data and then continuously replicate changes from the source MongoDB oplog to keep the target DocumentDB synchronized until cutover.

Exam trap

The trap here is that candidates often confuse AWS DataSync (file transfer) or Snowball Edge (offline bulk transfer) with database migration, but DMS is the only service that supports live, ongoing replication for heterogeneous database migrations like MongoDB to DocumentDB.

How to eliminate wrong answers

Option A is wrong because AWS DataSync is designed for moving large volumes of file data (e.g., NFS, SMB) to Amazon S3 or EFS, not for migrating databases with ongoing replication. Option C is wrong because Amazon S3 is an object storage service and cannot perform live database replication or schema conversion required for a MongoDB-to-DocumentDB migration. Option D is wrong because AWS Snowball Edge is a physical data transfer device for offline bulk data migration, which cannot support an online, minimal-downtime migration with continuous replication.

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114

MCQmedium

A company is deploying a new multi-AZ Aurora MySQL database. The application requires read-heavy workloads and low latency. Which configuration will best meet these requirements?

A.Enable Multi-AZ and use the secondary for read traffic.

B.Deploy a single instance with one read replica in the same AZ.

C.Enable Aurora Auto Scaling with a target metric of average CPU utilization.

D.Use an RDS Proxy in front of the database.

AnswerC

Aurora Auto Scaling adds reader instances automatically to handle read-heavy workloads, improving latency.

Why this answer

Aurora Auto Scaling dynamically adds reader instances based on the average CPU utilization metric, which directly addresses the read-heavy workload requirement by distributing read traffic across multiple replicas. This configuration ensures low latency by scaling out read capacity automatically as demand increases, without manual intervention.

Exam trap

The trap here is that candidates confuse Multi-AZ with read scaling, assuming the standby instance can serve reads, but in Aurora Multi-AZ, the secondary is a writer instance for failover only, not a reader.

How to eliminate wrong answers

Option A is wrong because in Aurora Multi-AZ, the secondary (writer) instance is not used for read traffic; it only provides failover support, and using it for reads would degrade write performance and violate Aurora's architecture. Option B is wrong because deploying a single instance with one read replica in the same AZ does not provide high availability or fault tolerance, and a single replica cannot handle heavy read loads effectively, leading to potential latency issues. Option D is wrong because RDS Proxy manages connection pooling and reduces database load from connection churn, but it does not directly address read-heavy workloads or scale read capacity; it is a connection management tool, not a read scaling solution.

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115

MCQmedium

A company is deploying a new web application on AWS. The application uses Amazon RDS for MySQL as its database. The database must be highly available and automatically failover in the event of an AZ outage. The company also needs to offload read traffic from the primary database to improve performance. The application read-to-write ratio is 80:20. The database workload is variable, with occasional spikes. The company wants a cost-effective solution that scales read capacity automatically. The operations team has limited experience with AWS. Which solution should the company implement?

A.Deploy an RDS for MySQL instance with Multi-AZ and one or more read replicas, and use Application Auto Scaling to add replicas based on CPU utilization

B.Deploy an RDS for MySQL instance with Multi-AZ and enable automatic scaling of the instance size

C.Deploy an Amazon Aurora MySQL cluster with Multi-AZ and enable Aurora Auto Scaling for read replicas

D.Deploy an RDS for MySQL instance with multiple read replicas and use a custom script to promote a read replica in case of failure

AnswerC

Aurora provides automatic failover and auto-scaling of read replicas, and is MySQL-compatible, making it a cost-effective and simpler solution.

Why this answer

This solution is correct because Amazon Aurora is MySQL-compatible, provides high availability and automatic failover through its Multi-AZ deployment, and includes Aurora Auto Scaling which automatically adjusts the number of read replicas based on workload, scaling read capacity automatically. This is cost-effective as you pay only for the replicas you use and it requires minimal management, making it ideal for teams with limited AWS experience. Option A is incorrect because read replicas do not auto-scale automatically; Application Auto Scaling for replicas requires custom setup.

Option B is incorrect because scaling instance size does not offload read traffic or provide read scaling. Option D is incorrect because it lacks automatic failover and requires manual intervention.

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116

Multi-Selectmedium

A company is migrating a 200 GB Oracle database to Amazon Aurora MySQL. They want to minimize downtime and ensure data consistency. Which two services should they use together? (Choose TWO.)

Select 2 answers

A.AWS Snowball Edge

B.AWS Schema Conversion Tool (SCT)

C.AWS Database Migration Service (DMS)

D.AWS Data Pipeline

E.Amazon EC2 with Oracle installed

AnswersB, C

SCT converts Oracle schema to Aurora MySQL.

Why this answer

AWS Schema Conversion Tool (SCT) is required to convert the Oracle database schema (including stored procedures, functions, and data types) to a format compatible with Amazon Aurora MySQL. AWS Database Migration Service (DMS) then performs the continuous data replication from Oracle to Aurora MySQL, enabling near-zero downtime migration while maintaining data consistency through Change Data Capture (CDC).

Exam trap

The trap here is that candidates often assume AWS DMS alone can handle heterogeneous migrations, forgetting that SCT is mandatory for schema conversion when moving from Oracle to Aurora MySQL, as DMS only handles data movement and cannot convert incompatible database objects.

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117

MCQhard

A company is deploying a new web application using Amazon RDS for PostgreSQL. The application requires read-heavy workloads and automatic failover. Which configuration should be used?

A.Multi-AZ deployment without Read Replicas

B.Single-AZ with a Read Replica in the same region

C.Multiple Read Replicas in different regions

D.Multi-AZ deployment with one or more Read Replicas

AnswerD

Provides HA and read scaling.

Why this answer

A Multi-AZ deployment provides automatic failover to a standby instance in a different Availability Zone, ensuring high availability. Adding one or more Read Replicas offloads read-heavy workloads from the primary instance, improving performance. This combination meets both the read-heavy and automatic failover requirements for the application.

Exam trap

The trap here is that candidates often assume Multi-AZ alone handles read scaling, but it does not; the standby in Multi-AZ is not accessible for reads, so Read Replicas are required for read-heavy workloads.

How to eliminate wrong answers

Option A is wrong because while Multi-AZ provides automatic failover, it does not include Read Replicas, so read-heavy workloads would still hit the primary instance, causing performance bottlenecks. Option B is wrong because Single-AZ with a Read Replica lacks automatic failover; if the primary fails, the Read Replica must be manually promoted, causing downtime. Option C is wrong because multiple Read Replicas in different regions address read scaling but do not provide automatic failover; failover requires a Multi-AZ deployment or manual promotion.

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118

Multi-Selecthard

A company is deploying a new Amazon RDS for Oracle database in a VPC. The database must be accessed by an application running on an EC2 instance in a different subnet. Which THREE steps are required to allow this access?

Select 3 answers

A.Create a VPC peering connection between the subnets.

B.Attach an Internet Gateway to the VPC.

C.Configure the network ACL for the RDS subnet to allow inbound traffic from the EC2 subnet.

D.Ensure the VPC has the 'Enable DNS hostnames' attribute set to true.

E.Add an inbound rule to the RDS security group that allows traffic from the EC2 security group.

AnswersC, D, E

NACLs provide stateless filtering.

Why this answer

The security group of the RDS instance must allow inbound traffic from the EC2 security group, which is option E. The VPC must have the 'Enable DNS hostnames' attribute set to true (option D) so that the RDS endpoint resolves correctly. Additionally, the network ACL for the RDS subnet must allow inbound traffic from the EC2 subnet (option C).

Option A (VPC peering) is not needed because both resources are in the same VPC. Option B (Internet Gateway) is not needed because traffic is within the VPC and does not require internet access.

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119

Multi-Selectmedium

A company needs to migrate a 1 TB Oracle database to Amazon RDS for Oracle. The migration must have minimal downtime and the source database is running on-premises. Which TWO AWS services should be used together to achieve this?

Select 2 answers

A.AWS Database Migration Service (DMS)

B.AWS Schema Conversion Tool (SCT)

C.AWS CloudEndure Migration

D.AWS Snowball

E.AWS Direct Connect

AnswersA, D

AWS DMS is correct. It handles the full load and CDC replication for minimal downtime.

Why this answer

To migrate a 1 TB Oracle database to Amazon RDS for Oracle with minimal downtime, two services are required. AWS Database Migration Service (DMS) performs the initial full load and then uses Change Data Capture (CDC) to continuously replicate ongoing changes, minimizing downtime. AWS Direct Connect establishes a dedicated network connection between the on-premises environment and AWS, ensuring stable and high-bandwidth data transfer necessary for the large database migration.

Without Direct Connect, the replication could be impacted by internet latency or outages.

Exam trap

The trap is that candidates may assume AWS DMS alone is sufficient for a homogeneous migration. However, for a 1 TB database with minimal downtime, a dedicated network service like AWS Direct Connect is essential to maintain consistent throughput. Candidates might incorrectly choose AWS SCT, which is only needed for heterogeneous migrations, or AWS Snowball, which is for offline transfer and not suitable for minimal downtime.

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120

MCQeasy

A company wants to deploy a DynamoDB table that requires consistent single-digit millisecond latency regardless of traffic spikes. Which DynamoDB capacity mode should be selected?

A.DynamoDB Accelerator (DAX) enabled.

B.Provisioned capacity mode with auto scaling.

C.On-demand capacity mode.

D.Provisioned capacity mode with fixed read/write capacity.

AnswerC

Automatically scales to handle any traffic level.

Why this answer

On-demand capacity mode is the correct choice because it automatically scales read and write capacity up and down based on actual traffic, eliminating the need for capacity planning and ensuring consistent single-digit millisecond latency even during unpredictable traffic spikes. This mode is designed for workloads with variable or bursty traffic patterns where latency sensitivity is critical.

Exam trap

The DBS-C01 exam often tests the misconception that DAX is a capacity mode or that auto scaling provides instant burst protection, when in fact only on-demand mode guarantees zero throttling during sudden traffic spikes without pre-provisioning.

How to eliminate wrong answers

Option A is wrong because DynamoDB Accelerator (DAX) is an in-memory caching service that reduces read latency but does not change the capacity mode; it is an add-on, not a capacity mode itself. Option B is wrong because provisioned capacity with auto scaling adjusts capacity based on utilization metrics, but it cannot react instantly to sudden traffic spikes, potentially causing throttling and latency degradation during rapid bursts. Option D is wrong because fixed provisioned capacity requires manual capacity planning and cannot handle traffic spikes without risking throttling or excessive cost, leading to inconsistent latency.

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121

MCQmedium

Refer to the exhibit. An IAM policy is attached to an IAM user that performs database migrations. When the user tries to start an AWS DMS replication task that writes to the RDS instance 'targetdb', the task fails with an access denied error. Which additional permission is required?

A.dms:CreateEndpoint

B.dms:CreateReplicationInstance

C.dms:DescribeReplicationInstances

D.rds:ModifyDBInstance on the source database

AnswerC

The user may need to describe replication instances to select one for the task.

Why this answer

The DMS replication task requires permission to describe the replication instance that is being used to run the task. The `dms:DescribeReplicationInstances` action allows the IAM user to retrieve metadata about the replication instance, which DMS needs to validate the instance state and configuration before starting the task. Without this permission, the start task operation fails with an access denied error even if the user has permissions to start the task itself.

Exam trap

The trap here is that candidates assume the error is due to missing permissions for the target database (RDS) or for creating resources, when in fact DMS requires read-only describe permissions on the replication instance to validate its state before starting a task.

How to eliminate wrong answers

Option A is wrong because `dms:CreateEndpoint` is used to create source or target endpoints, not to start an existing replication task; the error occurs during task start, not endpoint creation. Option B is wrong because `dms:CreateReplicationInstance` is required to provision a new replication instance, but the task failure is about starting a task on an existing instance, not creating one. Option D is wrong because `rds:ModifyDBInstance` on the source database is unrelated to starting a DMS task; the error is from DMS, not from RDS, and modifying the source database is not a prerequisite for task execution.

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122

MCQmedium

A company is migrating a 2 TB Oracle database to Amazon Aurora PostgreSQL. They need to minimize downtime and ensure data consistency. Which migration strategy should they use?

A.Use AWS DMS with full load only, then cut over during a maintenance window.

B.Use AWS DMS with ongoing replication (change data capture) from Oracle to Aurora.

C.Export the database to Amazon S3 using Oracle Data Pump, then import into Aurora.

D.Use pg_dump to export the database and pg_restore to import into Aurora.

AnswerB

DMS CDC captures ongoing changes, allowing near-zero downtime migration.

Why this answer

AWS DMS with ongoing replication (change data capture) is the correct strategy because it allows continuous synchronization of changes from the source Oracle database to the target Aurora PostgreSQL, minimizing downtime to just the final cutover window. This approach ensures data consistency by applying transactional changes in near real-time, which is essential for a 2 TB database where a full load alone would require a lengthy maintenance window and risk data divergence.

Exam trap

The trap here is that candidates often assume a full-load-only approach (Option A) is sufficient for large databases, underestimating the downtime required to stop writes and the risk of data inconsistency, while overlooking that DMS's ongoing replication is the only option that combines minimal downtime with continuous data synchronization.

How to eliminate wrong answers

Option A is wrong because full load only captures a point-in-time snapshot; any changes made after the load starts are lost, requiring a long maintenance window to stop all writes, which contradicts the goal of minimizing downtime. Option C is wrong because exporting to Amazon S3 using Oracle Data Pump and then importing into Aurora is a manual, offline process that requires the source database to be quiesced or taken offline, causing significant downtime and lacking built-in change data capture for ongoing sync. Option D is wrong because pg_dump and pg_restore are PostgreSQL-native tools that cannot connect to or extract data from an Oracle source database; they are designed for PostgreSQL-to-PostgreSQL migrations only.

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123

MCQhard

A company is planning to migrate a 5 TB Oracle data warehouse to Amazon Redshift. They need to transform the data during migration. Which AWS service should they use to perform the transformation?

A.Amazon Kinesis Data Analytics for real-time transformation.

B.Amazon Athena to query the source data and write results to Redshift.

C.AWS Glue to perform extract, transform, and load (ETL) jobs.

D.AWS Database Migration Service (DMS) with transformation rules.

AnswerC

Glue is a fully managed ETL service suitable for transforming data before loading into Redshift.

Why this answer

AWS Glue is the correct choice because it is a fully managed ETL service designed for data transformation and loading into Amazon Redshift. It can handle the 5 TB Oracle data warehouse migration by running Spark-based ETL jobs that transform the data before writing it to Redshift, making it ideal for batch-oriented data warehouse migrations.

Exam trap

The trap here is that candidates often confuse AWS DMS's transformation rules (which handle simple schema mapping) with the full ETL capabilities needed for data warehouse migration, leading them to choose DMS instead of Glue.

How to eliminate wrong answers

Option A is wrong because Amazon Kinesis Data Analytics is for real-time stream processing, not for batch ETL transformations of a 5 TB data warehouse migration. Option B is wrong because Amazon Athena is an interactive query service for data in S3, not a tool for performing ETL transformations and loading data into Redshift; it cannot directly write transformed data to Redshift. Option D is wrong because AWS DMS with transformation rules is primarily for schema and data type conversions during live migration, not for complex data transformations required in a data warehouse migration; it lacks the ETL capabilities needed for significant data reshaping.

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124

MCQeasy

A company wants to migrate an on-premises MongoDB database to Amazon DocumentDB. The migration should be performed with minimal application changes. Which AWS service should be used?

A.Amazon S3 Transfer Acceleration

B.AWS DataSync

C.AWS Schema Conversion Tool (AWS SCT)

D.AWS Database Migration Service (AWS DMS)

AnswerD

AWS DMS can migrate data from MongoDB to DocumentDB with minimal application changes.

Why this answer

AWS DMS is the correct service because it supports homogeneous migrations from MongoDB to Amazon DocumentDB, including ongoing replication via change data capture (CDC) to minimize downtime. It handles schema conversion automatically for compatible data types, requiring minimal application changes since DocumentDB is MongoDB-compatible. AWS DMS can migrate data directly from a MongoDB source to a DocumentDB target without needing an intermediate schema transformation tool.

Exam trap

The trap here is that candidates may choose AWS SCT thinking schema conversion is always required, but for a homogeneous migration to a MongoDB-compatible target like DocumentDB, AWS DMS alone handles both schema and data migration without needing SCT.

How to eliminate wrong answers

Option A is wrong because Amazon S3 Transfer Acceleration is used to speed up uploads to S3 over long distances, not for database migration or replication. Option B is wrong because AWS DataSync is designed for moving large datasets between on-premises storage and AWS storage services (e.g., S3, EFS, FSx), not for database migration or ongoing replication. Option C is wrong because AWS Schema Conversion Tool (AWS SCT) is used for heterogeneous database migrations (e.g., Oracle to Aurora) to convert schema and code, but it is not needed for a homogeneous migration from MongoDB to DocumentDB, and it does not perform the actual data migration.

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125

MCQhard

A company is migrating a 2 TB Oracle database running on an on-premises Linux server to Amazon RDS for Oracle. The migration must have minimal downtime and must be fully reversible if any issues arise. The DBA has configured AWS DMS with a full load and ongoing replication task. The full load completes successfully, and CDC is replicating changes. During the cutover window, the DBA stops the source database and promotes the target RDS instance. However, after cutover, the application team reports that some recent transactions are missing from the target database. The DBA confirms that the DMS task showed a 'healthy' status before stopping. Which action should the DBA take to resolve the issue and prevent recurrence?

A.Rebuild the entire migration using a native Oracle export/import tool.

B.Increase the replication instance size to improve throughput.

C.Restart the DMS task from the beginning to recapture the missing data.

D.Before stopping the source database, run the 'Stop task' command with the '--apply-immediately' option to ensure all cached changes are written to the target.

AnswerD

This ensures that all remaining CDC changes are applied before stopping.

Why this answer

In AWS DMS, after full load completes, ongoing replication (CDC) accumulates changes in a cache. To ensure no data loss during cutover, the DBA should stop the source database and then issue a 'Stop task' command with the '--apply-immediately' option (or use the 'Last Stop' job in the console) to flush all cached changes to the target before stopping the task. Option A (native export/import) would cause significant downtime and is unnecessary.

Option B (increasing instance size) improves throughput but does not capture remaining cached changes. Option C (restarting from the beginning) would lose already migrated data and is not a targeted fix. Only option D directly addresses the issue of missing transactions by ensuring all CDC cached changes are applied before the task is stopped.

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126

MCQeasy

A company is deploying a new application that requires a highly available DynamoDB table with eventual consistency. The table will be accessed from multiple AWS Regions. What is the most appropriate deployment strategy?

A.Use DynamoDB auto scaling to handle regional traffic

B.Use DynamoDB Accelerator (DAX) to cache data across regions

C.Use DynamoDB global tables

D.Use DynamoDB Streams to replicate data to another region

AnswerC

Global tables provide managed multi-region replication with eventual consistency.

Why this answer

DynamoDB global tables provide a fully managed, multi-Region, multi-active solution that automatically replicates data across selected AWS Regions, delivering eventual consistency and high availability for applications accessed from multiple Regions. This is the most appropriate strategy because it natively supports the requirement without custom code or additional infrastructure.

Exam trap

The trap here is that candidates may confuse DynamoDB Streams (a single-Region change capture mechanism) with global tables (which use Streams internally for multi-Region replication), leading them to choose Option D as a DIY approach instead of the managed global tables service.

How to eliminate wrong answers

Option A is wrong because DynamoDB auto scaling adjusts read/write capacity within a single Region based on traffic, but it does not replicate data across Regions or provide multi-Region access. Option B is wrong because DAX is an in-memory cache for a single Region; it does not replicate data across Regions and cannot provide multi-Region eventual consistency. Option D is wrong because DynamoDB Streams capture item-level changes in a single Region and require custom application logic to replicate data to another Region, which adds complexity and is not a managed multi-Region solution.

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127

MCQmedium

A company is migrating a 2 TB Oracle database from on-premises to Amazon RDS for Oracle. The database has a 4-hour maintenance window and the migration must have minimal downtime. Which AWS service should be used for the migration?

A.Use AWS Schema Conversion Tool (SCT) to convert the schema and then perform a full data load.

B.Create an RDS Cross-Region Read Replica and promote it to a standalone instance.

C.Use AWS Database Migration Service (DMS) with ongoing replication from the source database.

D.Take a full backup of the on-premises database, upload it to S3, and restore it to RDS.

AnswerC

AWS DMS can perform continuous replication, minimizing downtime.

Why this answer

AWS DMS with ongoing replication (change data capture) is the correct choice because it allows you to perform a full load of the 2 TB Oracle database and then continuously replicate incremental changes from the source to the target RDS instance. This minimizes downtime by enabling a cutover window of minutes rather than hours, which is critical given the 4-hour maintenance window constraint.

Exam trap

The trap here is that candidates often confuse AWS SCT with DMS, assuming SCT can handle ongoing replication, or they mistakenly think RDS Cross-Region Read Replicas can be created from an on-premises source, when in fact they only work between RDS instances.

How to eliminate wrong answers

Option A is wrong because AWS Schema Conversion Tool (SCT) is used for heterogeneous migrations (e.g., Oracle to Aurora PostgreSQL) and does not handle ongoing replication; it only converts schema and performs a one-time full load, which would cause extended downtime. Option B is wrong because RDS Cross-Region Read Replicas are only supported within RDS itself, not for on-premises databases; they cannot replicate from an external Oracle source. Option D is wrong because taking a full backup, uploading to S3, and restoring to RDS is a one-time bulk operation that does not capture ongoing changes, resulting in significant downtime during the backup and restore process.

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128

MCQeasy

A company needs to migrate a 2 TB PostgreSQL database from an on-premises data center to Amazon Aurora PostgreSQL. The network bandwidth is limited to 100 Mbps. The migration window is 5 days. Which approach is most cost-effective and likely to succeed?

A.Use AWS DMS with a VPN connection to the on-premises database

B.Set up AWS Direct Connect and use DMS

C.Use AWS Snowball Edge to transfer data offline

D.Export to Amazon S3 and import into Aurora

AnswerA

DMS can migrate online within bandwidth constraints.

Why this answer

AWS DMS with a VPN connection can handle the migration of 2 TB over 100 Mbps within 5 days. At 100 Mbps, the theoretical maximum transfer is about 1.08 TB per day (100 Mbps * 86400 seconds / 8 bits per byte / 1024^3), so 2 TB would take roughly 1.85 days of continuous transfer, well within the 5-day window. DMS supports ongoing replication to minimize downtime, and a VPN is cost-effective compared to Direct Connect for a one-time migration.

Exam trap

The trap here is that candidates often overestimate the need for offline transfer (Snowball) or expensive dedicated connections (Direct Connect) when the bandwidth and time window are actually sufficient for an online migration, leading them to ignore the cost-effectiveness of a VPN-based DMS approach.

How to eliminate wrong answers

Option B is wrong because AWS Direct Connect is more expensive to set up and provision than a VPN, and for a 2 TB migration over 100 Mbps, the bandwidth is sufficient without the additional cost and lead time of Direct Connect. Option C is wrong because AWS Snowball Edge is designed for offline transfer of large datasets (typically 10 TB+ or when bandwidth is extremely limited), but here the bandwidth is adequate and the migration window is long enough, making Snowball more costly and slower due to shipping and processing delays. Option D is wrong because exporting a 2 TB PostgreSQL database to Amazon S3 and then importing into Aurora is not a native or efficient method; it requires custom scripting, lacks built-in replication, and would likely exceed the 5-day window due to the overhead of export/import operations and lack of incremental sync.

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129

MCQmedium

A company is migrating a 500 GB Oracle database to Amazon RDS for Oracle. The migration must be completed within 24 hours with minimal downtime. The on-premises network bandwidth is 1 Gbps. The migration team plans to use AWS DMS with ongoing replication. During the initial load, the DMS task fails with an error indicating that the source database is experiencing high CPU utilization. The source database is a production system serving live traffic. The team needs to reduce the impact on the source database while still meeting the migration deadline. Which approach should the team take?

A.Change the DMS task to perform only full load and skip ongoing replication

B.Reduce the number of tables loaded in parallel in the DMS task and schedule the migration during off-peak hours

C.Increase the size of the DMS replication instance to speed up the migration

D.Use AWS Snowball to transfer the data offline and then use DMS for ongoing replication

AnswerB

This reduces source CPU load and still meets the deadline if off-peak window is sufficient.

Why this answer

The issue is that DMS is consuming too many resources on the source. Reducing the number of tables loaded in parallel and scheduling the migration during off-peak hours will reduce CPU impact. Option B is the most balanced.

Option A (increase DMS instance size) would increase source CPU usage. Option C (change to full load only) would require downtime. Option D (use Snowball) may not meet the 24-hour deadline due to shipping time.

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130

MCQmedium

A company is migrating a 1 TB Amazon RDS for Oracle database to Amazon RDS for PostgreSQL. The migration must be completed within a 4-hour maintenance window. The database has a high volume of transactions. Which migration method minimizes risk of data loss?

A.Use AWS SCT to convert the schema, then use AWS DMS for full load and ongoing replication.

B.Set up Oracle log shipping to an EC2 instance, then restore to RDS PostgreSQL.

C.Use AWS DMS with a full load and change data capture (CDC) enabled, with task restart and validation.

D.Export the Oracle database using Data Pump, import to PostgreSQL using pgloader.

AnswerC

CDC captures ongoing changes, task restart ensures reliability.

Why this answer

AWS DMS with full load and CDC enables continuous replication of ongoing transactions after the initial load, minimizing data loss risk during the migration window. The task restart and validation features ensure resilience against transient failures and data integrity checks, critical for a high-volume transactional database. This approach meets the 4-hour window by allowing the full load to complete within the window while CDC captures any changes that occur during and after the load.

Exam trap

The trap here is that candidates often assume AWS SCT plus DMS full load (Option A) is sufficient for minimal data loss, overlooking that CDC is required to capture ongoing transactions during the migration window.

How to eliminate wrong answers

Option A is wrong because using AWS SCT for schema conversion followed by DMS full load and ongoing replication lacks the CDC component, meaning any transactions occurring during the full load would be lost, increasing data loss risk. Option B is wrong because Oracle log shipping to an EC2 instance and then restoring to RDS PostgreSQL is not supported; RDS PostgreSQL does not accept Oracle log-shipped files, and this method introduces unnecessary complexity and potential data loss without native CDC. Option D is wrong because exporting with Oracle Data Pump and importing with pgloader is a one-time, offline migration that cannot capture ongoing transactions, leading to significant data loss if the database remains active during the migration window.

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131

MCQeasy

A company is migrating a 100 GB SQL Server database to Amazon RDS for SQL Server. They need to minimize downtime and ensure that only the schema is converted. Which tool should they use?

A.AWS Database Migration Service (DMS)

B.AWS Schema Conversion Tool (SCT)

C.AWS DMS with schema conversion enabled

D.SQL Server Management Studio (SSMS)

AnswerB

SCT is designed to convert database schema from one engine to another.

Why this answer

AWS Schema Conversion Tool (SCT) is the correct choice because it is specifically designed to convert database schemas (including stored procedures, functions, and data types) from one engine to another, such as SQL Server to Amazon RDS for SQL Server. Since the requirement is to minimize downtime and only convert the schema (not migrate data), SCT can perform an offline schema conversion without impacting the source database, whereas DMS is a continuous data replication tool that would incur downtime for schema changes.

Exam trap

The trap here is that candidates often confuse AWS DMS (which handles data replication) with AWS SCT (which handles schema conversion), and assume DMS can perform schema-only migrations without realizing it always includes data transfer and potential downtime.

How to eliminate wrong answers

Option A is wrong because AWS DMS is primarily a data migration service that replicates ongoing changes and requires a full load of data, which would cause downtime and does not focus on schema-only conversion. Option C is wrong because DMS with schema conversion enabled still performs data migration and schema conversion together, leading to unnecessary downtime and data transfer when only schema conversion is needed. Option D is wrong because SQL Server Management Studio (SSMS) can generate schema scripts but does not automate conversion to RDS SQL Server's specific dialect or handle compatibility issues, and it would require manual intervention and potential downtime.

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132

MCQhard

A financial services company is migrating a 500 GB Oracle database to Amazon Aurora MySQL-Compatible Edition. The migration must have minimal downtime and support bidirectional replication for a test-and-cutover approach. The company currently uses Oracle GoldenGate for replication. Which migration strategy should be used?

A.Use AWS DMS with a full load and ongoing replication from Oracle to Aurora MySQL, then cut over.

B.Use AWS Schema Conversion Tool (SCT) to convert the schema and then use AWS DMS for a one-time full load.

C.Use AWS DMS with Oracle GoldenGate as a source for continuous replication to Aurora MySQL.

D.Use Oracle GoldenGate to replicate directly to Aurora MySQL, then cut over.

AnswerA

DMS supports ongoing replication for cross-engine migrations, enabling minimal downtime and test-and-cutover.

Why this answer

AWS DMS with full load and ongoing replication is the correct strategy because it supports minimal-downtime migration from Oracle to Aurora MySQL and can handle bidirectional replication for a test-and-cutover approach. DMS uses change data capture (CDC) from Oracle's redo logs to keep the target in sync, allowing you to validate the target before cutting over. This meets the requirement for minimal downtime and a test-and-cutover workflow without relying on Oracle GoldenGate.

Exam trap

The trap here is that candidates assume Oracle GoldenGate, which the company already uses, must be part of the migration strategy, but AWS DMS can directly handle the replication without GoldenGate, and GoldenGate does not support Aurora MySQL as a target.

How to eliminate wrong answers

Option B is wrong because AWS Schema Conversion Tool (SCT) only converts schema and a one-time full load does not provide ongoing replication or bidirectional support, so it cannot achieve minimal downtime. Option C is wrong because AWS DMS cannot use Oracle GoldenGate as a source for continuous replication; DMS uses its own CDC engine based on Oracle redo logs, not GoldenGate. Option D is wrong because Oracle GoldenGate does not natively support direct replication to Amazon Aurora MySQL-Compatible Edition as a target; GoldenGate requires a supported target database, and Aurora MySQL is not a certified GoldenGate target.

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133

MCQeasy

A company wants to migrate an on-premises MongoDB database to Amazon DocumentDB. The migration must be performed with minimal downtime and should support live data synchronization. Which AWS service should be used?

A.AWS Glue with streaming ETL jobs.

B.AWS Data Pipeline to schedule periodic data loads.

C.AWS S3 with AWS Lambda functions to sync data.

D.AWS Database Migration Service (DMS) with ongoing replication.

AnswerD

DMS can connect to MongoDB as source and DocumentDB as target with change data capture for minimal downtime.

Why this answer

AWS Database Migration Service (DMS) with ongoing replication is the correct choice because it supports continuous change data capture (CDC) from a source MongoDB database to Amazon DocumentDB, enabling live data synchronization with minimal downtime. DMS can perform a full load followed by ongoing replication using the MongoDB oplog to capture and apply changes in near real-time, which meets the requirement for minimal downtime during migration.

Exam trap

The trap here is that candidates may confuse AWS DMS's ongoing replication with batch-oriented services like Glue or Data Pipeline, assuming any 'sync' tool works, but only DMS provides native CDC from MongoDB's oplog for live migration to DocumentDB.

How to eliminate wrong answers

Option A is wrong because AWS Glue with streaming ETL jobs is designed for batch and stream processing of data for analytics, not for live database migration with minimal downtime; it lacks native support for capturing ongoing changes from a MongoDB oplog and applying them to DocumentDB. Option B is wrong because AWS Data Pipeline schedules periodic data loads, which introduces downtime between loads and cannot provide live synchronization or capture real-time changes. Option C is wrong because AWS S3 with AWS Lambda functions to sync data would require custom code to poll for changes and handle conflict resolution, and it cannot reliably replicate MongoDB's oplog-based CDC, leading to data inconsistency and higher latency.

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134

MCQhard

Refer to the exhibit. A company is creating an IAM policy for a migration engineer who needs to perform a database migration from an on-premises SQL Server to Amazon RDS for SQL Server using AWS DMS. The policy is attached to the engineer's IAM user. Which additional permission is required for the engineer to create a DMS replication instance?

A.kms:CreateKey

B.dms:CreateEndpoint

C.s3:PutObject

D.ec2:CreateInstance (or equivalent)

AnswerD

DMS replication instances require EC2 permissions to be created.

Why this answer

To create a DMS replication instance, AWS DMS launches an Amazon EC2 instance in the customer's VPC to run the replication engine. The IAM user must have permission to call ec2:RunInstances (or the equivalent ec2:CreateInstance action) to provision this underlying compute resource. Without this EC2 permission, the DMS service cannot spin up the replication instance, and the migration engineer will receive an authorization error.

Exam trap

The trap here is that candidates assume DMS replication instances are fully managed by AWS and require no EC2 permissions, but in reality DMS provisions EC2 instances in the customer's account, making ec2:RunInstances a mandatory permission.

How to eliminate wrong answers

Option A is wrong because kms:CreateKey is used to create a new AWS KMS key for encryption, but DMS can use an existing KMS key or the default AWS managed key; the engineer does not need to create a new key. Option B is wrong because dms:CreateEndpoint is a separate permission for creating source or target endpoints, not for creating the replication instance itself. Option C is wrong because s3:PutObject is required only if the migration involves storing task logs or using S3 as a target, but it is not needed to provision the replication instance.

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135

MCQeasy

A company is migrating an on-premises MySQL database to Amazon RDS for MySQL. The database has a table with 100 million rows. During the migration using AWS DMS, the full load phase is taking too long. What change can speed up the full load?

A.Increase the number of DMS task mappings (parallel threads)

B.Reduce the target RDS instance storage to minimize write latency

C.Increase the size of the source on-premises database instance

D.Disable LOB columns in the task settings

AnswerA

More threads can process data in parallel, speeding up full load.

Why this answer

Increasing the number of DMS task mappings (parallel threads) allows DMS to partition the source table and load multiple segments concurrently, significantly reducing the full load duration. By default, DMS uses a single thread per table; adding parallel threads leverages the source database's read capacity and the target RDS instance's write throughput more efficiently.

Exam trap

The DBS-C01 exam often tests the misconception that increasing source or target instance size is the primary lever for migration speed, when in fact DMS's parallelism settings directly control concurrency and are the most impactful change for full load performance.

How to eliminate wrong answers

Option B is wrong because reducing the target RDS instance storage does not minimize write latency; in fact, smaller storage volumes often have lower IOPS baselines and throughput limits, which can increase write latency and slow the load. Option C is wrong because increasing the size of the source on-premises database instance does not directly affect DMS's extraction speed; DMS reads from the source using SQL queries, and the bottleneck is typically DMS's own parallelism, not the source instance size. Option D is wrong because disabling LOB columns is not a valid DMS task setting; LOB handling can be configured (e.g., limited LOB mode), but disabling them entirely would omit data and is not a recommended method to speed up full load.

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136

MCQeasy

A company wants to migrate an on-premises Oracle database to Amazon RDS for Oracle with minimal downtime. Which AWS service should be used for the initial data load and ongoing replication?

A.AWS Database Migration Service (DMS)

B.AWS Snowball

C.AWS Direct Connect

D.AWS Schema Conversion Tool (SCT)

AnswerA

DMS supports full load and ongoing replication for minimal downtime.

Why this answer

AWS Database Migration Service (DMS) is the correct choice because it supports both full-load migration and ongoing change data capture (CDC) replication from Oracle to Amazon RDS for Oracle. DMS uses Oracle LogMiner or binary reader to capture incremental changes from the source database's redo logs, enabling near-zero downtime migration without requiring application modifications.

Exam trap

The trap here is that candidates often confuse AWS Snowball (a bulk data transfer appliance) with a migration tool suitable for minimal-downtime scenarios, failing to recognize that Snowball cannot handle ongoing replication or CDC from a live database.

How to eliminate wrong answers

Option B (AWS Snowball) is wrong because Snowball is a physical data transfer device for large-scale offline data movement, not a tool for ongoing replication or minimal-downtime migration; it cannot capture and apply continuous changes from an active Oracle database. Option C (AWS Direct Connect) is wrong because Direct Connect establishes a dedicated network connection between on-premises and AWS, but it does not perform data migration or replication itself; it only provides the network transport layer. Option D (AWS Schema Conversion Tool) is wrong because SCT is used to convert database schema and code from one engine to another (e.g., Oracle to PostgreSQL), not to migrate data or perform ongoing replication; it does not handle data movement or CDC.

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137

MCQhard

A company is migrating a 3 TB SQL Server database to Amazon RDS for SQL Server. The migration must be completed with less than 15 minutes of downtime. The company has set up AWS DMS with ongoing replication. During the final cutover, the DMS task fails with a 'Target error: Cannot insert duplicate key' error. What is the most likely cause?

A.The target table has an identity column that is not set to allow insert of explicit values.

B.The DMS task is not set to truncate the target before loading.

C.The source database transaction log is full.

D.The source database has a primary key violation.

AnswerA

If identity insert is off, DMS cannot insert source values, causing duplicate key errors.

Why this answer

The error 'Cannot insert duplicate key' during DMS full load or ongoing replication indicates that the target table has an identity column that does not allow explicit value insertion. By default, SQL Server identity columns are set to NOT FOR REPLICATION = OFF, meaning DMS cannot insert rows with explicit identity values, causing duplicate key violations when the source has identity values that conflict with the target's auto-generated sequence. To resolve this, you must set the identity column to allow explicit inserts (e.g., SET IDENTITY_INSERT ON) or configure DMS to use 'Do nothing' for identity handling.

Exam trap

The trap here is that candidates often confuse a target-side duplicate key error with a source-side primary key violation or think that truncating the target will fix all replication issues, but the real cause is the identity column's explicit insert restriction specific to SQL Server.

How to eliminate wrong answers

Option B is wrong because truncating the target before loading would not prevent duplicate key errors during ongoing replication; it only affects the initial full load, and the error occurs during the final cutover when replication is already running. Option C is wrong because a full transaction log on the source would cause a different error (e.g., 'Log full' or 'Cannot continue because log is full'), not a duplicate key violation on the target. Option D is wrong because a primary key violation on the source would be a source-side error, not a target-side 'Cannot insert duplicate key' error; DMS would report a source error, not a target constraint violation.

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138

Multi-Selecthard

A company is deploying a new Amazon RDS for Oracle instance and needs to ensure high availability and automatic failover. Which configuration should be used?

Select 1 answer

A.Read Replicas in a different Region

B.Multi-AZ deployment

C.Enhanced Monitoring

D.Automated backups with point-in-time recovery

E.Deletion protection

AnswersB

Correct. Multi-AZ creates a standby replica in a different AZ for automatic failover.

Why this answer

(Multi-AZ deployment) is correct because it provisions a synchronous standby replica in a different Availability Zone, enabling automatic failover without data loss when the primary instance fails. This meets the high availability and automatic failover requirements for Amazon RDS for Oracle. Option D (Automated backups with point-in-time recovery) provides backup and recovery capabilities but does not ensure high availability or automatic failover; it is not a configuration for automatic failover.

Exam trap

The trap here is that candidates often confuse Read Replicas with Multi-AZ, assuming read replicas provide automatic failover, but they require manual promotion and do not offer synchronous replication or automatic failover.

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139

MCQmedium

A company is migrating a 1 TB Microsoft SQL Server database to Amazon RDS for SQL Server using native backup and restore. The DBA has taken a full backup of the source database and uploaded it to an S3 bucket. The DBA then uses the 'aws rds restore-db-instance-from-db-snapshot' CLI command to restore the backup to an RDS instance. The restore fails with an error: 'Could not find the specified backup file in the S3 bucket.' The DBA verifies that the backup file exists in the correct S3 bucket and that the IAM role used by RDS has permissions to access the bucket. What is the most likely cause of the failure?

A.The backup file has an incorrect file extension, such as .trn instead of .bak.

B.The backup file is not encrypted with AWS KMS.

C.The RDS instance is not configured to use native restore.

D.The backup file is not placed in the correct S3 bucket path that includes the account ID prefix.

AnswerD

RDS expects the backup file to be in a path like 'bucket-name/account-id/filename'. If missing, it cannot find the file.

Why this answer

When restoring a native backup from S3 to RDS, the backup file must be stored in a path that includes the AWS account ID as a prefix (e.g., /123456789012/backup.bak). RDS for SQL Server expects this specific path structure to locate the file. Even if the file exists in the bucket and permissions are correct, a wrong path causes the 'Could not find the specified backup file' error.

Option A is wrong because the file extension is not the issue; RDS accepts .bak and .trn files. Option B is wrong because encryption is not required for native restore. Option C is wrong because native restore is a supported feature on RDS for SQL Server; the error is about file location, not configuration.

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140

Multi-Selecteasy

A company is migrating an on-premises MySQL database to Amazon RDS for MySQL. The database is 500 GB and the migration must have minimal downtime. Which TWO AWS services should be used together to accomplish this?

Select 2 answers

A.AWS App2Container

B.AWS CloudFormation

C.AWS DataSync

D.AWS Database Migration Service (AWS DMS)

E.AWS Schema Conversion Tool (AWS SCT)

AnswersD, E

AWS DMS handles data migration with minimal downtime.

Why this answer

AWS DMS (Option D) is correct because it is purpose-built for migrating databases with minimal downtime by continuously replicating changes from the source to the target using change data capture (CDC). AWS SCT (Option E) is correct because it assesses the source MySQL schema and automatically converts any incompatible objects (e.g., storage engines, functions) to be compatible with Amazon RDS for MySQL, ensuring a smooth migration. Together, they enable a near-zero-downtime migration by first performing a full load via DMS and then applying ongoing CDC replication until cutover.

Exam trap

The trap here is that candidates may confuse AWS DataSync (a file-transfer service) with a database migration tool, or assume CloudFormation can handle data migration because it can deploy RDS instances, but neither supports live database replication or schema conversion.

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141

MCQhard

A company is migrating a 10 TB PostgreSQL database from on-premises to Amazon RDS for PostgreSQL. They need to minimize downtime and have limited network bandwidth. Which approach is most appropriate?

A.Use AWS Database Migration Service (DMS) with a full load and ongoing replication to keep the target in sync.

B.Use pg_dump to export the database and pg_restore to import to RDS, then use DMS for replication.

C.Use AWS Snowball to transfer a physical backup to AWS, then use DMS for ongoing replication.

D.Use AWS Direct Connect to increase bandwidth and then use DMS for full load and replication.

AnswerC

Snowball handles the large initial load offline; DMS handles ongoing changes with minimal bandwidth.

Why this answer

The 10 TB database size combined with limited network bandwidth makes a direct online migration impractical due to prolonged transfer times. AWS Snowball allows you to physically ship the database backup to AWS, bypassing bandwidth constraints. After loading the backup into Amazon RDS, AWS DMS can perform ongoing change data capture (CDC) replication to synchronize any changes made during the transfer, minimizing downtime.

Exam trap

The trap here is that candidates often assume DMS can handle any data volume over any network, ignoring the practical reality that large datasets (e.g., 10 TB) over limited bandwidth require a physical transfer mechanism like Snowball to avoid days or weeks of migration time.

How to eliminate wrong answers

Option A is wrong because a full load via DMS over limited bandwidth would take an excessively long time for 10 TB, likely exceeding acceptable downtime windows and risking timeout or failure. Option B is wrong because pg_dump and pg_restore over a limited network would also be extremely slow for 10 TB, and using DMS afterward for replication does not solve the initial transfer bottleneck. Option D is wrong because AWS Direct Connect requires weeks to provision and may not be feasible for a one-time migration; it also does not address the immediate bandwidth limitation if the on-premises network itself is constrained.

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142

MCQmedium

A company is migrating a 5 TB MySQL database to Amazon RDS for MySQL. They need to minimize downtime. Which approach should they use?

A.Use Percona XtraBackup to take a backup and restore to RDS

B.Use mysqldump to export and import data

C.Use AWS DMS with full load and change data capture (CDC)

D.Use AWS DataSync to copy database files

AnswerC

Minimizes downtime with CDC.

Why this answer

AWS DMS with full load and change data capture (CDC) minimizes downtime by performing an initial full load of the 5 TB database while continuously replicating ongoing changes from the source. Once the full load completes and the target is nearly synchronized, you can cut over with minimal downtime, typically seconds to minutes. This approach is specifically designed for large-scale migrations with low downtime requirements.

Exam trap

The trap here is that candidates often choose mysqldump (Option B) because it is familiar, but they overlook its inability to handle CDC and the impracticality of exporting 5 TB with minimal downtime.

How to eliminate wrong answers

Option A is wrong because Percona XtraBackup creates a physical backup of the MySQL data files, but restoring to RDS requires additional steps like uploading to S3 and using the mysql_restore tool, which does not support CDC and thus cannot minimize downtime for a live database. Option B is wrong because mysqldump is a logical backup tool that exports data as SQL statements, which is extremely slow for 5 TB and requires the source database to be read-locked or offline during the export, causing significant downtime. Option D is wrong because AWS DataSync is designed for copying files over NFS or SMB, not for direct database migration; it cannot handle MySQL's internal file structure or ongoing transactional changes, and would require the database to be stopped to ensure consistency.

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143

MCQmedium

A company is migrating a 1 TB SQL Server database from on-premises to Amazon RDS for SQL Server. The database has a large table with a LOB column. The network bandwidth between the on-premises data center and AWS is limited to 50 Mbps. The migration must be completed within a week. Which approach should the company use?

A.Use BCP to export the LOB table to flat files and then import to RDS.

B.Use SQL Server native backup and restore to RDS.

C.Use AWS DMS with compression enabled.

D.Create a read replica of the on-premises database and promote it.

AnswerC

DMS supports compression to reduce data transfer time.

Why this answer

AWS DMS with compression enabled is the correct approach because it can migrate the 1 TB database within the limited 50 Mbps bandwidth by compressing data during transfer, reducing the total data volume. DMS supports ongoing replication and handles LOB columns efficiently, making it suitable for a time-constrained migration. The 50 Mbps link can transfer approximately 1.5 TB in a week (50 Mbps * 604,800 seconds / 8 = ~3.78 TB raw capacity), but compression and overhead make DMS the most reliable choice for this scenario.

Exam trap

The trap here is that candidates often assume native backup and restore is universally supported for RDS migrations, but RDS for SQL Server restricts this to specific versions and requires the backup file to be uploaded to S3 first, which still faces bandwidth limitations without compression.

How to eliminate wrong answers

Option A is wrong because BCP exports LOB data to flat files, which are uncompressed and require additional storage and manual import steps, and the transfer over 50 Mbps would likely exceed the one-week window due to the large data volume without compression. Option B is wrong because SQL Server native backup and restore to RDS is not supported for on-premises to RDS migrations; RDS for SQL Server does not allow restoring native backups from external sources unless using the native backup/restore feature with S3, which still requires uploading the backup file and does not inherently compress data for transfer. Option D is wrong because creating a read replica of the on-premises database and promoting it is not feasible; SQL Server does not support cross-environment read replicas between on-premises and RDS, and this approach would require complex log shipping or replication setup that is not natively available.

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144

MCQhard

A company is migrating a 2 TB Oracle database to Amazon RDS for Oracle. The migration requires minimal downtime. They use AWS SCT to convert the schema and AWS DMS for data migration. After the full load, DMS ongoing replication is unable to capture changes because the archived redo logs are being deleted on the source before DMS can read them. The source database has a log retention setting of 2 hours. The team cannot increase the retention due to storage constraints. What should they do?

A.Switch to a full load only migration strategy.

B.Disable archiving on the source database.

C.Increase the DMS replication instance size to improve log reading speed.

D.Configure DMS to use an S3 bucket to store archived redo logs.

AnswerD

Correct: Configuring DMS to use an S3 bucket to store archived redo logs provides a temporary staging area, allowing DMS to read the logs before they are deleted. This solves the issue without increasing log retention on the source.

Why this answer

AWS DMS supports storing archived redo logs in an S3 bucket as a staging area, which allows DMS to process the logs before they are deleted from the source. This resolves the issue without requiring increased log retention on the source. Option A (full load only) would cause downtime.

Option B (disabling archiving) would prevent DMS from capturing ongoing changes. Option C (increasing DMS instance size) does not affect log reading speed from archived logs.

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145

MCQhard

An administrator runs the CLI command shown in the exhibit and sees the output. The DB instance 'mydb' is currently running MySQL 5.7.22. What does the output indicate?

A.The master user password has been changed

B.The DB instance has failed to apply modifications

C.The DB instance is using a custom DB parameter group

D.The DB instance has a pending minor version upgrade to 5.7.23

AnswerD

The EngineVersion in PendingModifiedValues indicates a pending upgrade.

Why this answer

The output shows 'Pending maintenance: Yes' with 'Minor version upgrade to 5.7.23' listed. This indicates that the DB instance has a pending minor version upgrade that will be applied during the next maintenance window. The CLI command 'aws rds describe-db-instances --db-instance-identifier mydb' returns this information when a minor version upgrade is scheduled but not yet applied.

Exam trap

The trap here is that candidates may confuse 'Pending maintenance' with a failed modification or a password change, but RDS clearly separates pending maintenance actions (like version upgrades) from immediate modifications (like password changes) in the CLI output.

How to eliminate wrong answers

Option A is wrong because changing the master user password would not appear as a pending maintenance action; it would be reflected in the 'MasterUsername' field and is applied immediately without a pending state. Option B is wrong because the output does not show any error or failure state; 'Pending maintenance: Yes' is a normal status indicating a scheduled action, not a failure to apply modifications. Option C is wrong because using a custom DB parameter group would be shown in the 'DBParameterGroup' field of the output, not as a pending maintenance action; the pending maintenance field specifically tracks upgrades and patches.

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146

MCQhard

A company needs to migrate a 10 TB SQL Server database from on-premises to Amazon RDS for SQL Server with minimal downtime. The database is heavily used with frequent write operations. Which migration strategy should be used?

A.Use native SQL Server backup and restore to Amazon S3, then restore to RDS.

B.Export the database to CSV files, upload to S3, and use the COPY command in RDS.

C.Use AWS Schema Conversion Tool (SCT) to convert the schema, then use AWS DMS for full load.

D.Use AWS DMS with ongoing replication from the on-premises database to RDS until cutover.

AnswerD

DMS ongoing replication enables minimal downtime by keeping the target current.

Why this answer

AWS DMS with ongoing replication (change data capture) allows a full load of the 10 TB database followed by continuous replication of write operations from the on-premises SQL Server to Amazon RDS for SQL Server. This minimizes downtime by keeping the target database synchronized until the cutover window, where only a brief pause is needed to apply final changes and switch traffic.

Exam trap

The trap here is that candidates often assume native backup/restore (Option A) is the simplest approach for large databases, but they overlook the requirement for minimal downtime and the fact that DMS with CDC is specifically designed for near-zero downtime migrations with ongoing writes.

How to eliminate wrong answers

Option A is wrong because native SQL Server backup and restore to S3 and then to RDS requires the database to be offline or in read-only mode during the backup and restore process, causing significant downtime for a heavily used database with frequent writes. Option B is wrong because exporting a 10 TB database to CSV files is impractical due to schema complexity, foreign keys, and the need to stop writes to maintain consistency; the COPY command in RDS is for loading flat files, not for ongoing replication. Option C is wrong because AWS SCT is used for schema conversion when migrating to a different database engine (e.g., SQL Server to Aurora), not for a homogeneous SQL Server to SQL Server migration, and DMS alone without ongoing replication would still require downtime for the final sync.

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147

MCQmedium

A company has a self-managed Redis cluster that needs to be migrated to Amazon ElastiCache for Redis. The cluster is 100 GB in size and has a high write throughput. The migration must have minimal downtime. Which steps should be taken?

A.Use AWS DMS to migrate the data with ongoing replication

B.Take a snapshot of the source and restore to ElastiCache

C.Use the SAVE command to create a dump, upload to S3, and import to ElastiCache

D.Set up replication from the source to ElastiCache using Redis replication

AnswerD

Replication allows minimal downtime by continuously syncing changes.

Why this answer

Redis replication (using the REPLICAOF or SLAVEOF command) allows you to set up the ElastiCache cluster as a read-replica of the self-managed Redis cluster, enabling continuous, asynchronous replication with minimal downtime. Once the replica is fully synchronized, you can promote it to the primary role with a brief failover, achieving a near-zero-downtime migration. This approach is ideal for a 100 GB cluster with high write throughput, as it avoids the performance impact of snapshotting or dump/restore operations.

Exam trap

The trap here is that candidates often assume AWS DMS is a universal migration tool for any data store, but it does not support Redis, making option A a tempting but incorrect choice.

How to eliminate wrong answers

Option A is wrong because AWS DMS does not support Redis as a source or target for ongoing replication; DMS is designed for relational databases and some NoSQL stores like DynamoDB, but not for Redis. Option B is wrong because taking a snapshot of a 100 GB cluster with high write throughput would cause significant performance degradation and potential data inconsistency, and restoring from a snapshot requires downtime that may be unacceptable. Option C is wrong because the SAVE command is a blocking operation that halts all client writes until the dump completes, causing downtime; additionally, uploading to S3 and importing to ElastiCache is a manual, offline process that does not support ongoing replication.

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148

MCQeasy

A company wants to migrate its on-premises Oracle database to Amazon Aurora PostgreSQL. The company needs to convert the database schema and code from Oracle to PostgreSQL. Which AWS service should they use for schema conversion?

A.AWS DMS

B.AWS Glue

C.AWS Schema Conversion Tool (SCT)

D.AWS Database Migration Service

AnswerC

SCT converts Oracle schemas to PostgreSQL.

Why this answer

AWS Schema Conversion Tool (SCT) is the correct choice because it is specifically designed to convert database schemas, stored procedures, functions, and other code objects from one database engine to another, such as Oracle to Amazon Aurora PostgreSQL. It analyzes the source schema and generates a target schema with equivalent PostgreSQL syntax, handling data type mappings, PL/SQL to PL/pgSQL conversion, and other compatibility issues. AWS DMS handles data migration but does not perform schema or code conversion.

Exam trap

The trap here is that candidates often confuse AWS DMS with schema conversion, assuming DMS can handle both data and schema migration, but DMS only moves data and requires SCT for schema transformation.

How to eliminate wrong answers

Option A (AWS DMS) is wrong because AWS Database Migration Service (DMS) is a data migration tool that moves data between databases, but it does not convert schema or code objects like stored procedures or triggers; it relies on SCT for schema conversion. Option B (AWS Glue) is wrong because AWS Glue is a serverless data integration service for ETL (Extract, Transform, Load) jobs, primarily used for data preparation and analytics, not for converting database schemas between different engines. Option D (AWS Database Migration Service) is essentially the same as Option A and is wrong for the same reason: it handles data replication and migration, not schema or code conversion.

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149

MCQeasy

A company needs to migrate a 100 GB MongoDB database to Amazon DocumentDB (with MongoDB compatibility). The migration must have minimal impact on the source database performance. Which approach should the company take?

A.Use AWS Database Migration Service (AWS DMS) with ongoing replication from the MongoDB source.

B.Use AWS DataSync to transfer the MongoDB data files.

C.Set up a MongoDB replica set on Amazon EC2 and promote it to primary, then migrate to DocumentDB.

D.Use mongodump to export the data and mongorestore to import into DocumentDB.

AnswerA

AWS DMS supports ongoing change data capture (CDC) from MongoDB oplog, enabling continuous replication with minimal read overhead on the source. This satisfies the stem’s constraint of minimal performance impact, as CDC reads only the oplog rather than scanning the entire 100 GB collection, avoiding sustained load on the production database.

Why this answer

AWS DMS with ongoing replication is the correct approach because it supports continuous change data capture (CDC) from MongoDB, enabling a live migration with minimal performance impact on the source. DMS reads the MongoDB oplog to capture changes without locking the database, which is critical for a 100 GB production database. This allows the target DocumentDB to stay synchronized until cutover, reducing downtime and avoiding the need for a full export/import that would strain the source.

Exam trap

The trap here is that candidates often choose mongodump/mongorestore (Option D) as the simplest tool, overlooking that it causes significant source performance impact and downtime for large databases, while AWS DMS's CDC capability is specifically designed for minimal-impact migrations.

How to eliminate wrong answers

Option B is wrong because AWS DataSync is designed for file-based transfers (e.g., NFS, SMB) and cannot directly read MongoDB's internal data files or handle the BSON format; it would require stopping the database to ensure consistency, causing significant impact. Option C is wrong because setting up a MongoDB replica set on EC2 and promoting it to primary involves complex manual steps, potential downtime, and does not directly migrate to DocumentDB; it also requires managing EC2 instances and does not leverage AWS-managed services for minimal impact. Option D is wrong because mongodump and mongorestore perform a full logical dump, which locks the source database during the dump (or requires a secondary read), causing performance degradation on a 100 GB database; it also lacks ongoing replication, leading to longer downtime.

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150

Multi-Selecteasy

A company is migrating a PostgreSQL database to Amazon Aurora PostgreSQL. They want to use the AWS DMS for the migration. Which THREE resources need to be created in the AWS account?

Select 3 answers

A.Application Load Balancer for the replication instance.

B.AWS CloudFormation stack to provision resources.

C.DMS target endpoint pointing to Aurora PostgreSQL.

D.DMS replication instance.

E.DMS source endpoint pointing to the PostgreSQL database.

AnswersC, D, E

The target endpoint defines the connection to the target database.

Why this answer

AWS DMS requires a target endpoint that specifies the connection details for the Amazon Aurora PostgreSQL database. This endpoint tells DMS where to load the migrated data, and it must be configured with the correct database name, credentials, and VPC settings to ensure successful connectivity during the migration task.

Exam trap

The trap here is that candidates might think CloudFormation is mandatory for provisioning DMS resources, but the exam tests that only the replication instance and both endpoints are the core required components for a DMS migration task.

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