DBS-C01 Practice Exam 58 — 20 Questions

Question 1

A company wants to migrate a 500 GB SQL Server database to Amazon RDS for SQL Server with the least amount of downtime. The on-premises network has a 1 Gbps connection to AWS. Which approach should be used?

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

Accepted Answer

Use AWS DMS with ongoing replication from on-premises to RDS. AWS DMS with ongoing replication (change data capture, CDC) allows you to perform a full load of the 500 GB database while continuously replicating ongoing changes from the on-premises SQL Server to Amazon RDS for SQL Server. This minimizes downtime to a brief cutover window when you stop writes on the source and redirect traffic to the target. The 1 Gbps connection is sufficient for the initial load and ongoing replication, making this the most effective approach for minimal downtime.

Answer

Use AWS Snowball to transfer the database backup, then restore to RDS

Answer

Copy database files to S3 and then use RDS import

Answer

Use native SQL Server backup to S3, then restore to RDS

Question 2

A company is designing a database for an e-commerce platform that stores product catalog data. The catalog has frequent reads and occasional writes. The data is highly relational but the team wants the lowest possible latency for read queries. Which database service should they choose?

Accepted Answer

Amazon DynamoDB with DAX. Amazon DynamoDB with DAX is the best choice because the workload requires the lowest possible latency for read queries on a highly relational product catalog with frequent reads and occasional writes. DynamoDB provides single-digit millisecond latency at scale, and DAX (DynamoDB Accelerator) is an in-memory cache that reduces read latency to microseconds for eventually consistent reads, directly addressing the low-latency requirement without sacrificing the ability to handle occasional writes.

Answer

Amazon DocumentDB

Answer

Amazon RDS for PostgreSQL with read replicas

Answer

Amazon ElastiCache for Redis

Question 3

A DevOps engineer notices that an Amazon DynamoDB table's read capacity is frequently throttled during peak hours. The table has read-once, read-many workload. Which action is MOST cost-effective to reduce throttling?

Accepted Answer

Enable DynamoDB Accelerator (DAX). DynamoDB Accelerator (DAX) caches frequently read items, reducing the number of read requests to the table. For a read-once, read-many workload, this significantly lowers read capacity consumption, thus reducing throttling cost-effectively. Option A is incorrect: Enabling auto-scaling for read capacity would help reduce throttling by automatically adjusting capacity, but it does not reduce the number of reads; it increases capacity when needed, which can be more expensive than using DAX. Option C is incorrect: Switching to On-Demand capacity mode eliminates throttling by paying per request, but for a predictable, high-read workload, this is typically more expensive than provisioned capacity with DAX. Option D is incorrect: Increasing the provisioned read capacity units would reduce throttling, but it increases cost because you pay for higher capacity even during off-peak hours. DAX is more cost-effective as it reduces the required capacity.

Answer

Enable auto-scaling for read capacity

Answer

Switch to On-Demand capacity mode

Answer

Increase the provisioned read capacity units

Question 4

A company is using Amazon DynamoDB with provisioned capacity. The application is experiencing throttling on write requests. The database specialist needs to identify the cause. Which TWO metrics should be reviewed in CloudWatch? (Select TWO.)

Accepted Answer

ConsumedWriteCapacityUnits. 'ConsumedWriteCapacityUnits' shows the actual write capacity used, helping to determine if provisioned capacity is exceeded, which leads to throttling. Option B is correct because 'WriteThrottleEvents' directly indicates the number of throttled write requests. Option C is incorrect because 'ThrottledWriteRequests' is not a valid CloudWatch metric for DynamoDB; the correct metric for throttled writes is 'WriteThrottleEvents'. Option D is incorrect because 'ReadThrottleEvents' pertains to read throttling, not writes. Option E is incorrect because 'SuccessfulRequestLatency' measures latency, not throttling events.

Answer

ThrottledWriteRequests

Answer

ReadThrottleEvents

Answer

SuccessfulRequestLatency

Question 5

A company is migrating a 500 GB MongoDB database to Amazon DocumentDB. The migration must have minimal impact on the source database. Which approach should the company take?

Accepted Answer

Use AWS Database Migration Service (DMS) with MongoDB as source and DocumentDB as target.. AWS DMS supports ongoing replication from MongoDB to Amazon DocumentDB, enabling a live migration with minimal impact on the source database. DMS uses the MongoDB oplog to capture changes continuously, so the source is only read during the initial load and then tailed for CDC, avoiding heavy locks or performance degradation.

Answer

Use mongodump to export the data, then use mongorestore to import into DocumentDB.

Answer

Use mongoexport to export CSV, then use the DocumentDB import tool.

Answer

Use AWS Schema Conversion Tool (SCT) to convert schema, then copy data.

Question 6

A company is running a MongoDB-compatible Amazon DocumentDB cluster. The application experiences high write latency during peak hours. The database administrator checks the CloudWatch metrics and notices that the Write IOPS metric is consistently at the maximum for the instance size. What should the administrator do to reduce write latency?

Accepted Answer

Increase the instance size to a larger instance class with higher IOPS limits.. Increasing the instance size provides more IOPS capacity, which can reduce write latency if the instance is hitting IOPS limits. Option B is incorrect because switching to a memory-optimized instance class does not directly increase IOPS capacity; it improves memory performance, not I/O throughput. Option C is incorrect because increasing allocated storage size may increase IOPS if using gp2, but the issue is hitting the maximum IOPS for the current instance, and simply increasing storage does not guarantee a proportional increase in IOPS limits. Option D is incorrect because enabling Multi-AZ adds a standby replica for high availability but does not offload writes or increase write IOPS capacity on the primary.

Answer

Switch to a memory-optimized instance class.

Answer

Increase the allocated storage size to improve I/O performance.

Answer

Enable Multi-AZ deployment to offload writes to the standby.

Question 7

A database administrator notices that an Amazon RDS for MySQL instance's storage is filling up unexpectedly. The administrator has enabled automated backups and retains them for 7 days. Which of the following actions would help reduce storage consumption without losing the ability to perform point-in-time recovery?

Accepted Answer

Reduce the backup retention period to 1 day. Reducing the backup retention period reduces the amount of storage consumed by automated backup data, while still allowing point-in-time recovery for the duration of the retention period. Option A is incorrect because changing the instance class does not affect storage consumption. Option C is incorrect because deleting manual snapshots does not reduce the automated backup storage that is likely causing the unexpected filling, and manual snapshots are not necessary for point-in-time recovery. Option D is incorrect because disabling automated backups eliminates point-in-time recovery capability.

Answer

Modify the DB instance to a smaller instance class

Answer

Delete manual DB snapshots

Answer

Disable automated backups

Question 8

A company is migrating an on-premises Oracle database to Amazon Aurora PostgreSQL. The migration uses AWS Database Migration Service (DMS) with ongoing replication. The team notices that the target Aurora database is falling behind the source during peak hours. Which of the following actions would MOST effectively improve the replication performance?

Accepted Answer

Configure the DMS task to use 'Limited LOB mode' and increase the max LOB size. The most effective action. Using 'Limited LOB mode' in AWS DMS reduces the overhead of replicating large objects by only transferring metadata until the LOB is accessed, and increasing the max LOB size ensures that LOBs fit within a single transaction, preventing fragmentation. Option A is incorrect because disabling Multi-AZ does not directly affect DMS replication performance; Multi-AZ provides high availability but does not impact replication throughput. Option B, increasing the Aurora instance size, may help if the instance is CPU or memory constrained, but the primary bottleneck in replication is often the handling of large objects, making DMS task configuration more targeted. Option C is incorrect because using a smaller instance would worsen performance, not improve it.

Answer

Disable Multi-AZ on the target Aurora cluster

Answer

Increase the Amazon Aurora instance size

Answer

Use a smaller Aurora instance to reduce write latency

Question 9

A company's security team wants to encrypt data at rest for an existing RDS for PostgreSQL DB instance. The instance is currently unencrypted. Which steps should the team take to enable encryption with minimal downtime?

Accepted Answer

Take a snapshot of the DB instance, copy the snapshot with encryption enabled, and restore a new DB instance from the encrypted snapshot.. Amazon RDS does not support enabling encryption directly on an existing unencrypted DB instance. The only supported method is to take a snapshot of the instance, copy the snapshot with encryption enabled, and restore a new DB instance from the encrypted snapshot. Option A is incorrect because the RDS console does not allow enabling encryption on an existing instance. Option B is incorrect because a read replica of an unencrypted instance is also unencrypted; promoting it does not add encryption. Option C is incorrect because option groups control database engine configuration, not encryption at rest. Encryption at rest is a storage-level feature that can only be enabled during instance creation or via snapshot operations.

Answer

Modify the DB instance and enable encryption in the RDS console.

Answer

Create a read replica of the DB instance and promote it to a standalone instance.

Answer

Create a new option group with encryption enabled and associate it with the DB instance.

Question 10

A developer is using AWS Database Migration Service (DMS) to migrate a database from on-premises to Amazon RDS. The migration task is failing with 'Insufficient memory' error. Which resource should be increased to resolve this?

Accepted Answer

Increase the size of the DMS replication instance.. The DMS replication instance may have insufficient memory. Increasing its size provides more memory. Option B is wrong because source database memory is not controlled by DMS. Option C is wrong because S3 is not involved in the DMS process by default. Option D is wrong because target RDS instance memory may not be the bottleneck.

Answer

Increase the memory on the source database.

Answer

Increase the Amazon S3 bucket size for staging.

Answer

Increase the memory on the target RDS instance.

Question 11

A company is planning to migrate a MongoDB database to Amazon DocumentDB. The database has several sharded collections. Which migration strategy should be used?

Accepted Answer

Use AWS DMS with MongoDB as source and DocumentDB as target, enabling ongoing replication.. AWS DMS supports MongoDB as a source and Amazon DocumentDB as a target, and it can perform ongoing replication (change data capture) to keep the target synchronized with the source during migration. This is essential for sharded MongoDB collections because it minimizes downtime by allowing the source to remain operational while data is migrated and changes are continuously applied.

Answer

Set up MongoDB replica set to replicate directly to DocumentDB.

Answer

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

Answer

Export data using mongodump and import using mongorestore.

Question 12

A company is migrating a legacy Oracle data warehouse to Amazon Redshift. The source uses complex stored procedures with cursors, temporary tables, and PL/SQL. Which THREE design considerations should the company evaluate?

Accepted Answer

Redshift does not support procedural languages like PL/SQL; stored procedures must be rewritten in SQL or Python.. Amazon Redshift does not support Oracle's PL/SQL procedural language; stored procedures must be rewritten using Redshift's PL/pgSQL or Python UDFs (option A). Redshift supports temporary tables, but they are session-scoped and must be explicitly dropped or they persist until session ends (option B). Redshift does not support cursors as in Oracle; result sets must be handled using alternative methods such as fetching into arrays or using LIMIT/OFFSET (option D). These are key migration considerations.

Answer

Redshift Concurrency Scaling can handle thousands of concurrent queries.

Answer

Redshift automatically scales compute capacity based on workload.

Question 13

A company is designing a new e-commerce platform using Amazon DynamoDB. The workload requires single-digit millisecond latency for user session data, which is accessed by session token. The session data is temporary and should be automatically deleted after 24 hours. Which DynamoDB design should the database specialist recommend?

Accepted Answer

Enable DynamoDB Time to Live (TTL) on the session token attribute. DynamoDB Time to Live (TTL) automatically deletes expired items after a specified timestamp, making it ideal for session data that must be removed after 24 hours. This approach requires no additional infrastructure, meets the single-digit millisecond latency requirement by using the session token as the primary key, and ensures automatic cleanup without manual intervention or added cost.

Answer

Create an AWS Lambda function that runs every hour and deletes expired session data

Answer

Store session data in Amazon S3 with a lifecycle policy to delete objects after 24 hours

Answer

Use DynamoDB Accelerator (DAX) to cache session data and set a 24-hour TTL on the cache

Question 14

A company has a multi-AZ RDS for PostgreSQL DB instance. The security team wants to ensure that database audit logs are stored in CloudWatch Logs for real-time monitoring. The team enabled the 'pgaudit.log' parameter and set 'log_destination' to 'csvlog'. However, logs are not appearing in CloudWatch. What is the most likely cause?

Accepted Answer

The 'rds.logs_to_cloudwatch' parameter is not set to 1.. RDS publishes logs to CloudWatch only if the 'rds.logs_to_cloudwatch' parameter is set to 1. Option A is wrong because multi-AZ does not prevent log delivery. Option B is wrong because CloudTrail is not involved in log delivery to CloudWatch; it's about API activity logging. Option C is wrong because the DB parameter group is associated; the issue is that the specific parameter 'rds.logs_to_cloudwatch' is not set.

Answer

The DB instance is multi-AZ, which prevents log delivery to CloudWatch.

Answer

AWS CloudTrail is not enabled for the RDS instance.

Answer

The DB parameter group is not associated with the DB instance.

Question 15

A database specialist needs to capture SQL queries executed against an Amazon Aurora MySQL DB cluster for performance analysis. The capture should have minimal performance impact and be stored in Amazon CloudWatch Logs. Which feature should the specialist use?

Accepted Answer

Enable Performance Insights and configure the Performance Insights log export to CloudWatch Logs.. Performance Insights captures SQL queries with minimal overhead by sampling the database engine's internal wait states and query activity, then exports this data to CloudWatch Logs for analysis. This approach is designed for performance monitoring without the significant performance impact of enabling full logging (like the general log), making it ideal for capturing queries for performance analysis.

Answer

Enable the slow query log and export to CloudWatch Logs.

Answer

Enable database audit logs and export to CloudWatch Logs.

Answer

Enable the general log and publish to CloudWatch Logs.

Question 16

A security engineer is designing a solution to encrypt data at rest for an Amazon Redshift cluster. The company requires that the encryption key be rotated automatically every year. Which solution meets these requirements?

Accepted Answer

Enable encryption for the Redshift cluster using an AWS KMS key with automatic rotation.. Amazon Redshift supports encryption at rest using AWS KMS with automatic key rotation. When you enable encryption for a Redshift cluster, you can choose a KMS key with automatic rotation enabled, which meets the requirement of rotating the encryption key automatically every year.

Option A is incorrect because manual rotation using a Lambda function is not the recommended approach when automatic rotation is available. Redshift does not support custom manual rotation; it relies on KMS for key management.

Option C is incorrect because Redshift does not support CloudHSM for encryption at rest; it uses AWS KMS. CloudHSM does not provide automatic rotation as a built-in feature in the same way KMS does.

Option D is incorrect because Redshift does not store cluster data in an S3 bucket; S3 server-side encryption is not applicable to the Redshift cluster itself. Redshift uses its own encryption mechanism integrated with KMS.

Answer

Use a Lambda function to rotate the encryption key manually every year.

Answer

Use a CloudHSM key to encrypt the Redshift cluster and configure automatic rotation in CloudHSM.

Answer

Store the Redshift cluster data in an S3 bucket with server-side encryption enabled.

Question 17

A database administrator is troubleshooting connectivity to an Amazon RDS for MySQL DB instance. The application is running on an EC2 instance in the same VPC and security group. The application can connect using the endpoint shown in the exhibit. However, the security team requires that all connections be encrypted using SSL. The DBA has enabled SSL on the DB instance and modified the parameter group to set require_secure_transport to ON. The application is now failing to connect. What is the most likely cause?

Accepted Answer

The application's JDBC connection string does not include SSL parameters such as useSSL=true.. When require_secure_transport is set to ON, the database server rejects non-SSL connections. The application must be configured to use SSL by adding the useSSL=true and requireSSL=true parameters to the JDBC connection string. Option A is incorrect because the application could connect before SSL was enforced, indicating that DNS resolution was working. Option B is incorrect because the server enforces SSL at the transport level, and no separate SSL privilege is needed for the user account. Option D is incorrect because SSL connections use the same port as non-SSL (3306 for MySQL), and the security group was already configured to allow traffic on that port.

Answer

The DB instance endpoint is not resolving to the correct IP address.

Answer

The database user account does not have the SSL privilege granted.

Answer

The security group does not allow inbound traffic on port 3307, which is used for SSL connections.

Question 18

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database contains personally identifiable information (PII). The security team requires that all PII columns be transparently encrypted and that the encryption keys be stored in AWS CloudHSM. Which solution meets these requirements?

Accepted Answer

Use Oracle Transparent Data Encryption (TDE) with AWS CloudHSM as the key store.. Oracle Transparent Data Encryption (TDE) with AWS CloudHSM as the key store enables transparent encryption of PII columns and stores the encryption keys in CloudHSM, meeting the security requirements. Option A is wrong because Amazon RDS encryption at rest uses AWS KMS, not CloudHSM, and it encrypts the entire database instance, not specific columns. Option B is wrong because modifying an Oracle database to use AWS KMS for column-level encryption is not supported natively in RDS; Oracle TDE is required for transparent column encryption. Option C is wrong because Oracle Data Pump is an export/import utility, not a column-level encryption solution; it does not provide transparent encryption of PII columns in the live database.

Answer

Enable Amazon RDS encryption at rest using a KMS key and rely on that encryption.

Answer

Modify the Oracle database to use AWS KMS for column-level encryption.

Answer

Use Oracle Data Pump to export data with encryption and store the encryption key in AWS Secrets Manager.

Question 19

A company uses Amazon Redshift for data warehousing. The security team requires that all data be encrypted at rest with a customer-managed key, and that the key be rotated every year. Which configuration meets these requirements?

Accepted Answer

Launch the Redshift cluster with encryption enabled using a customer-managed KMS key with automatic annual rotation.. Amazon Redshift supports encryption at rest using a KMS key. You can enable automatic key rotation on a customer-managed KMS key. Option A is wrong because launching without encryption and enabling later using CloudHSM is not supported; Redshift does not support enabling encryption after launch without reloading data, and CloudHSM requires manual key rotation. Option B is wrong because Redshift does not use S3-managed keys for encryption; you must use a KMS key or HSM. Option C is correct because it meets the requirements. Option D is wrong because using an HSM for key storage does not provide automatic key rotation; you would need to rotate the key manually.

Answer

Launch the Redshift cluster without encryption and enable encryption later using AWS CloudHSM.

Answer

Launch the Redshift cluster with encryption enabled using an S3-managed key.

Answer

Launch the Redshift cluster with encryption enabled using a KMS key and configure the cluster to use an HSM for key storage.

Question 20

A company is migrating a 5 TB Microsoft SQL Server database to Amazon RDS for SQL Server. The migration must have minimal downtime. The source database is hosted on an EC2 instance. Which combination of steps should be taken?

Accepted Answer

Take a native backup of the source, upload to S3, and restore to RDS. Native backup and restore to Amazon RDS for SQL Server is the fastest and most reliable method for migrating a large database like 5 TB with minimal downtime. By taking a full backup, uploading it to Amazon S3, and restoring it to RDS, you avoid the overhead of ongoing replication setup and can schedule the final cutover during a brief maintenance window. This approach leverages RDS's native support for restoring from S3, ensuring data integrity and minimizing the migration window.

Answer

Use AWS DMS with full load and ongoing replication

Answer

Create an RDS read replica from the EC2-hosted database

Answer

Use the SQL Server Import and Export Wizard