DBS-C01 Practice Test 36 — 15 Questions

Question 1

A security team is investigating a potential data breach in an Amazon RDS for SQL Server database. They need to determine which user executed a specific DELETE statement at a particular time. What should they do?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Enable audit logs for the RDS instance and send them to CloudWatch Logs.. Enabling audit logs for the RDS for SQL Server instance captures detailed SQL statement execution, including the users and timestamps. Sending these logs to CloudWatch Logs allows for easy searching and alerting. Option B is correct because it directly addresses the need to identify the user who executed a specific SQL statement. Option A is incorrect because AWS CloudTrail logs API actions (e.g., creating or modifying RDS instances), not SQL queries. Option C is incorrect because VPC Flow Logs capture network traffic metadata, not database-level activity. Option D is incorrect because AWS Trusted Advisor provides best-practice checks and does not offer fine-grained auditing.

Answer

Enable AWS CloudTrail for the RDS instance.

Answer

Enable VPC Flow Logs for the database subnet.

Answer

Enable AWS Trusted Advisor.

Question 2

A company is building a real-time analytics dashboard for IoT sensor data. The data arrives as JSON and needs to be stored in a way that supports fast ingestion and complex queries. Which database service is best suited?

Accepted Answer

Amazon Timestream. Amazon Timestream is purpose-built for time-series data, offering fast ingestion of JSON sensor data and optimized storage for time-based queries. It automatically manages retention, compression, and tiering (memory and magnetic store), enabling complex analytical queries (e.g., window functions, interpolation) without manual tuning. This makes it ideal for real-time IoT analytics dashboards.

Answer

Amazon RDS for PostgreSQL

Answer

Amazon DynamoDB with TTL

Answer

Amazon Redshift

Question 3

A company wants to migrate a 500 GB MySQL database from an on-premises server to Amazon RDS for MySQL. The migration must be completed within a 2-hour downtime window. Which migration approach is MOST suitable?

Accepted Answer

Create a compressed backup using Percona XtraBackup, upload it to S3, and restore it to RDS.. Percona XtraBackup allows you to create a physical backup of the MySQL database that can be compressed and uploaded to Amazon S3, then restored directly to an Amazon RDS for MySQL instance. This approach is significantly faster than logical backups (like mysqldump) for a 500 GB database, as it bypasses SQL parsing and rebuilds the data files directly, enabling completion within a 2-hour downtime window.

Answer

Use AWS Database Migration Service (DMS) with a full load.

Answer

Use mysqldump to export the database and then import it into RDS.

Answer

Create an RDS Read Replica of the on-premises database and promote it.

Question 4

A company wants to enforce encryption in transit for all connections to their ElastiCache for Redis cluster. Which security measure should they implement?

Accepted Answer

Enable Encryption in-transit when creating the cluster.. ElastiCache for Redis enforces encryption in transit by enabling the feature at cluster creation time. This uses TLS to encrypt data moving between clients and the Redis nodes, ensuring that all connections are secured against eavesdropping or man-in-the-middle attacks. The setting cannot be changed after the cluster is provisioned, so it must be enabled during the initial setup.

Answer

Set a parameter group with 'require_secure_transport' to ON.

Answer

Use VPC Flow Logs to monitor connections.

Answer

Enable encryption at rest using KMS.

Question 5

A company is using Amazon RDS for MySQL with Multi-AZ deployment. The application team reports intermittent connection timeouts. CloudWatch shows increased DatabaseConnections and CPU Utilization during peak hours. Which action should the database specialist take to troubleshoot the issue?

Accepted Answer

Enable slow query log and analyze queries.. Enabling the slow query log allows the database specialist to identify long-running or inefficient queries that contribute to high CPU utilization and increased database connections, leading to connection timeouts during peak hours. Option A is incorrect because Enhanced Monitoring provides additional metrics (e.g., OS-level metrics) but does not directly address the root cause of the timeouts; it is useful for deeper analysis but not the primary troubleshooting action. Option C is incorrect because creating a read replica and redirecting read traffic reduces load on the primary for read operations, but the issue likely involves write-intensive or poorly optimized queries affecting the primary; while it might alleviate some load, it is not a direct troubleshooting step to identify the cause. Option D is incorrect because failing over to the standby instance is for high availability and disaster recovery, not for resolving performance issues; it would restart the database but not fix the underlying queries or resource contention.

Answer

Add enhanced monitoring to collect additional metrics.

Answer

Create a read replica and redirect read traffic.

Answer

Failover to the standby instance to refresh connections.

Question 6

A financial services company is designing a ledger system using Amazon QLDB. The application records transactions that must never be modified or deleted. The company expects high write throughput and needs to ensure that the ledger can handle the load without throttling. Which design consideration is MOST important to achieve this?

Accepted Answer

Batch multiple document inserts into a single transaction to reduce the number of transactions.. Amazon QLDB charges per transaction (document insert, update, or delete) and has a maximum throughput limit of 1,000 transactions per second per ledger. By batching multiple document inserts into a single transaction, you reduce the number of transactions, thereby staying within the throughput limit while still achieving high write throughput. This approach directly addresses the need to avoid throttling without sacrificing the immutability requirements of the ledger system.

Answer

Partition the ledger table by transaction date to distribute write load.

Answer

Create multiple ledgers and distribute writes across them.

Answer

Enable auto-scaling on the ledger to handle bursts of traffic.

Question 7

A company is migrating an on-premises Oracle OLTP database to Amazon Aurora PostgreSQL. The database has a complex schema with stored procedures, triggers, and sequences. During the migration, the team notices that the conversion tool reports several incompatibilities. Which strategy should the team use to handle the database schema changes with minimal downtime?

Accepted Answer

Use AWS Database Migration Service (DMS) with the AWS Schema Conversion Tool (SCT) to convert the schema and migrate data, then handle remaining incompatibilities during a cutover window.. AWS DMS with SCT is the recommended approach for heterogeneous migrations like Oracle to Aurora PostgreSQL. SCT converts the schema (including stored procedures, triggers, and sequences) and identifies incompatibilities, while DMS handles ongoing replication to minimize downtime. The remaining incompatibilities can be resolved during a planned cutover window, which is the standard strategy for complex schema migrations with minimal downtime.

Answer

Deploy Amazon RDS for PostgreSQL with Babelfish to run Oracle PL/SQL code natively.

Answer

Use pg_dump and pg_restore to migrate the schema, and then test and fix any errors.

Answer

Manually rewrite all stored procedures and triggers to PostgreSQL syntax before migration.

Question 8

Refer to the exhibit. A database specialist is taking a final snapshot of an RDS DB instance before deletion. The command returns the output shown. The snapshot is at 75% progress. What should the specialist do next?

Accepted Answer

Wait for the snapshot status to become 'available' before deleting the instance.. An RDS DB instance cannot be deleted while a final snapshot is in progress; the snapshot must reach the 'available' status first. The AWS CLI output shows the snapshot at 75% progress, meaning the snapshot is still being created. Attempting to delete the instance before the snapshot completes will result in an error, as the deletion operation requires the snapshot to be fully available.

Answer

Use the describe-db-snapshots command with --db-snapshot-identifier to get more details.

Answer

Use the stop-db-instance command to pause the snapshot.

Answer

Delete the DB instance immediately; the snapshot will continue in the background.

Question 9

A company is migrating an on-premises MongoDB database to Amazon DocumentDB. The application uses secondary indexes extensively and requires low-latency reads. Which database design consideration is MOST important for this workload?

Accepted Answer

Convert secondary indexes to the DocumentDB-compatible format. Secondary indexes in MongoDB must be converted to the Amazon DocumentDB-compatible format. DocumentDB uses a different storage engine and indexing implementation than MongoDB, so indexes created in MongoDB are not automatically compatible. Converting secondary indexes ensures that the query patterns relying on those indexes continue to perform with low-latency reads after migration.

Answer

Provision EBS-optimized instances with increased IOPS

Answer

Use a larger instance type to avoid indexing issues

Answer

Enable DynamoDB Accelerator (DAX) for caching

Question 10

A company is migrating a 3 TB Oracle database to Amazon RDS for Oracle. The migration uses AWS DMS with ongoing replication. The source database is actively used by applications. After the initial full load, the target RDS instance is in sync. However, during the ongoing replication phase, the replication task fails with an error: 'ORA-1555: snapshot too old.' The DMS task has been set up with a source endpoint that uses the 'Oracle TNS' connection method. The company needs to resolve the issue without stopping the source database. Which action should be taken?

Accepted Answer

Increase the undo retention period in the source Oracle database.. The ORA-1555 error indicates that undo data is overwritten before DMS can read it. Increasing undo retention ensures the snapshot data is available longer. Reducing batch size would not address the undo issue. Increasing logging frequency does not affect undo. Using a different connection method does not solve the underlying undo retention problem.

Answer

Change the source endpoint to use the 'Oracle SID' connection method.

Answer

Decrease the batch size of the DMS task.

Answer

Increase the frequency of the DMS task's log mining.

Question 11

An IAM policy is attached to an IAM user. The user wants to connect to an RDS MySQL database using IAM database authentication. What does this policy allow?

Accepted Answer

Allows the user to connect to the RDS instance with the database user name 'db_user1'.. IAM database authentication allows an IAM user to authenticate to an RDS MySQL database using an IAM user or role. The IAM policy must include the rds-db:connect action with a resource ARN specifying the RDS instance and the database user name. When the resource ARN includes 'db_user1', the policy only permits connection as that specific database user, not as any user. Option A is incorrect because the policy does not grant permissions to any database or any user; it is scoped to 'db_user1'. Option B is incorrect because the rds-db:connect action does not grant management of the RDS instance. Option D is incorrect because the resource ARN restricts to 'db_user1', so connecting with any other database user name would be denied.

Answer

Allows the user to connect to any database on the RDS instance as any user.

Answer

Allows the user to manage the RDS instance.

Answer

Allows the user to connect to the RDS instance with any database user name.

Question 12

A mobile gaming application uses Amazon DynamoDB to store player profiles and game state. The write throughput is high during events, but low otherwise. The company wants to minimize costs while maintaining performance. Which capacity mode should they use?

Accepted Answer

On-Demand capacity mode. On-Demand capacity mode is ideal for this workload because it automatically scales to handle high write throughput during events and scales down to zero when idle, eliminating the need for capacity planning. This minimizes costs by charging only for actual reads and writes, without requiring any provisioning or management of throughput limits.

Answer

Reserved capacity

Answer

Provisioned capacity without auto scaling

Answer

Provisioned capacity with auto scaling

Question 13

A company needs to migrate a 100 GB on-premises SQL Server database to Amazon RDS for SQL Server. The migration must be completed within a 4-hour maintenance window. The network link has 500 Mbps throughput. Which approach should be used?

Accepted Answer

Use native SQL Server backup to S3, then restore to RDS. Native SQL Server backup to S3 and restore to RDS is the fastest method for a 100 GB database over a 500 Mbps link. At 500 Mbps, the theoretical transfer time for 100 GB is approximately 28 minutes (100 GB * 8 / 500 Mbps), well within the 4-hour window, making Snowball unnecessary. This approach avoids the overhead of change data capture (CDC) and additional compute resources, directly leveraging SQL Server's native backup/restore capabilities.

Answer

Use AWS DMS with full load and CDC

Answer

Use AWS Snowball Edge to transfer the backup

Answer

Launch an EC2 instance with SQL Server, copy the database, and then migrate to RDS

Question 14

A company is using Amazon DynamoDB with provisioned capacity for a table that experiences unpredictable traffic spikes. The table's read capacity is often underutilized, but occasionally throttling occurs. Which THREE steps should be taken to improve performance and cost? (Choose THREE.)

Accepted Answer

Switch the table to on-demand capacity mode.. Switching to on-demand capacity mode eliminates the need to manage provisioned capacity, automatically scaling to handle unpredictable traffic spikes without throttling. This improves performance by preventing throttling during spikes and optimizes cost by charging only for consumed reads/writes, avoiding the waste of underutilized provisioned capacity.

Answer

Reduce the provisioned read capacity units to save cost.

Answer

Disable auto scaling to avoid cost fluctuations.

Question 15

An IAM role with the above trust policy is created. The role is then attached to an EC2 instance. The application on the EC2 instance tries to create an RDS DB instance using the AWS SDK. What will happen?

Accepted Answer

The call will fail because the role's permissions policy does not allow rds:CreateDBInstance. The call will fail because the IAM role attached to the EC2 instance lacks a permissions policy (e.g., an identity-based policy) that explicitly grants the `rds:CreateDBInstance` action. The trust policy shown in the question only defines which principal (the EC2 service) can assume the role, not what actions the role can perform. Without a permissions policy allowing RDS operations, the SDK call is denied by default.

Answer

The call will succeed because the trust policy grants permissions to EC2

Answer

The call will succeed because the trust policy allows EC2 to create RDS instances

Answer

The call will fail because the trust policy does not include the RDS service