DBS-C01 Practice Test 42 — 15 Questions

Question 1

A company is migrating a 3 TB SQL Server database to Amazon RDS for SQL Server. They have limited network bandwidth (100 Mbps) and need to complete the migration within 3 days. Which two approaches could meet the requirements? (Choose TWO.)

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

Accepted Answer

Use AWS Snowball to physically transfer a full database backup to AWS, then restore into RDS.. Option C is correct because AWS Snowball physically ships a full SQL Server backup (.bak file) to AWS, bypassing the 100 Mbps internet link entirely. Transferring 3 TB at 100 Mbps would take roughly 2.8 days of continuous transfer at theoretical maximum, leaving no margin for overhead, retries, or restore time, so Snowball reliably moves the bulk data and the backup can then be restored into RDS for SQL Server. Option D is correct because AWS DMS with ongoing replication performs a full load over the internet and then uses change data capture to keep the target in sync until cutover. The full load can be started immediately and DMS supports parallel load threads; the theoretical transfer time is about 2.8 days, and ongoing replication captures changes made during the load so cutover can occur once the bulk data is in place, making this a valid migration pattern. Option A is not ideal because exporting to a flat file and uploading 3 TB over a 100 Mbps link still requires transferring the full compressed dataset, which likely exceeds the 3-day limit and adds import complexity. Option B is not appropriate because AWS DataSync transfers files to S3, not directly into RDS, and still uses the limited network bandwidth. Option E is incorrect because a VPN does not increase bandwidth and a DMS full load only (without ongoing replication) does not support continuous change replication for cutover.

Answer

Export the database to a flat file, compress it, and upload to S3 via the internet, then import into RDS.

Answer

Use AWS DataSync to transfer the database files directly to Amazon S3.

Answer

Establish a VPN connection and use AWS DMS with full load only.

Question 2

A company is deploying a new Amazon DynamoDB table to support an application with unpredictable read patterns. The application requires consistent low-latency reads and the ability to handle sudden spikes in traffic without manual intervention. The database team wants to minimize operational overhead while ensuring cost-effectiveness. Which DynamoDB capacity mode should they choose?

Accepted Answer

On-demand capacity mode.. On-demand capacity mode is designed for unpredictable workloads, automatically scaling to handle traffic spikes without manual intervention. It eliminates the need for capacity planning and provides consistent low-latency performance. Provisioned modes require some level of planning and may not react quickly enough to sudden spikes, while DAX is a caching solution that does not address capacity management.

Answer

DynamoDB Accelerator (DAX) with provisioned capacity.

Answer

Provisioned capacity mode with reserved capacity.

Answer

Provisioned capacity mode with auto scaling enabled.

Question 3

A company is using Amazon ElastiCache for Redis as a caching layer for a web application. Users report that some cached data is missing, causing slower responses. Which ElastiCache feature should be checked first to understand key evictions?

Accepted Answer

Evictions metric in CloudWatch. The Evictions metric in CloudWatch directly tracks the number of keys evicted from the cache due to memory pressure. When ElastiCache for Redis reaches its maxmemory limit, it evicts keys according to the configured eviction policy (e.g., volatile-lru, allkeys-lru). Monitoring this metric first will confirm whether missing cached data is caused by evictions. Other metrics like CacheHits or CPUUtilization do not provide direct insight into eviction events.

Answer

ReplicationLag metric

Answer

CPUUtilization metric

Answer

CacheHits metric in CloudWatch

Question 4

A company runs a financial application that requires ACID transactions on a relational database. The workload has a high volume of writes and reads, and the team wants to minimize operational overhead. Which AWS database service should they choose?

Accepted Answer

Amazon Aurora (MySQL-compatible). Amazon Aurora (MySQL-compatible) is the correct choice because it provides full ACID transaction support required for a financial application, while delivering high throughput for both reads and writes through its distributed, SSD-backed storage architecture. Aurora also minimizes operational overhead by automating tasks like replication, backups, and failover, and it offers up to 5x the throughput of standard MySQL without requiring manual sharding or tuning.

Answer

Amazon RDS for Oracle

Answer

Amazon DynamoDB with transactions enabled

Answer

Amazon ElastiCache for Memcached

Question 5

A company is migrating an on-premises Oracle data warehouse to AWS. The warehouse contains 50 TB of data and runs complex queries that involve joins and aggregations. The team wants to minimize migration effort and cost while maintaining query performance. Which AWS service should they use?

Accepted Answer

Amazon Redshift. Amazon Redshift is purpose-built for large-scale data warehousing, supporting up to petabytes of data with massively parallel processing (MPP) architecture that efficiently handles complex joins and aggregations. It minimizes migration effort by supporting automated schema conversion from Oracle via the AWS Schema Conversion Tool (SCT) and cost-effective columnar storage with compression, making it the optimal choice for a 50 TB Oracle data warehouse migration.

Answer

Amazon RDS for Oracle

Answer

Amazon ElastiCache for Redis

Answer

Amazon DynamoDB

Question 6

A company wants to migrate a 10 TB Microsoft SQL Server database from on-premises to Amazon RDS for SQL Server. The migration must be completed within a week and minimize network bandwidth usage. Which approach is most suitable?

Accepted Answer

Use AWS Snowball Edge to transfer backup files, then restore to RDS. AWS Snowball Edge is the most suitable approach because it allows you to transfer the 10 TB database backup files physically, bypassing the internet entirely. This eliminates network bandwidth constraints and ensures the migration can be completed within a week, as the data is shipped to AWS and then restored to Amazon RDS for SQL Server using native restore operations.

Answer

Back up the database to Amazon S3 using AWS CLI

Answer

Set up AWS Direct Connect and use DMS

Answer

Use AWS DMS over the internet

Question 7

An administrator is troubleshooting an Amazon RDS for PostgreSQL instance that is experiencing high CPU utilization. The administrator has enabled Performance Insights. Which metric should be examined first to identify the queries consuming the most CPU?

Accepted Answer

db.load.avg. Performance Insights uses db.load.avg as its core metric, which represents the average number of active sessions (Average Active Sessions, or AAS) broken down by wait events, SQL statements, users, and hosts. When CPU is the bottleneck, db.load.avg filtered by the CPU wait event immediately shows which SQL statements are consuming the most CPU. This is the correct first metric to examine.

Answer

db.sessions

Answer

db.cpu.avg

Answer

db.bytes_sent

Question 8

A security engineer manages an Amazon Aurora PostgreSQL cluster that stores regulated data. Audit requirements mandate that all data at rest be encrypted with a customer-managed AWS KMS key, and that the key be automatically rotated every year. The engineer creates a new KMS customer-managed key with automatic rotation enabled and now needs to apply it to the existing cluster. The cluster currently uses an AWS-managed key (aws/rds). What should the engineer do to meet these requirements with the LEAST operational effort?

Accepted Answer

Create a snapshot of the cluster, copy the snapshot with the new customer-managed KMS key, restore a new cluster from that encrypted snapshot, and repoint applications to the new cluster.. Encryption keys on Aurora storage are fixed when the cluster is created and cannot be swapped by modifying or rebooting the cluster. The supported, low-effort method to move an encrypted cluster to a different customer-managed KMS key is to copy a snapshot using the target key and restore a new cluster from that copy, then redirect clients. This satisfies the customer-managed key and annual rotation requirements without a logical data migration.

Answer

Enable automatic rotation on the existing AWS-managed aws/rds key and continue using it for the cluster.

Answer

Use AWS Database Migration Service with change data capture to replicate the cluster into a new cluster that is encrypted with the customer-managed key.

Answer

Modify the existing Aurora cluster to use the new customer-managed KMS key, then reboot the writer instance to apply the change.

Question 9

Which THREE of the following are best practices for designing a DynamoDB table for a gaming leaderboard that updates scores frequently and supports queries for top players? (Choose 3.)

Accepted Answer

Use strongly consistent reads for the leaderboard queries. Option B is correct because strongly consistent reads ensure the leaderboard reflects the most recent score updates immediately after a write, which is critical when scores change frequently and players expect an accurate, up-to-date ranking. Option C is correct because a Global Secondary Index (GSI) with score as the sort key lets you efficiently query the highest scores using Query with ScanIndexForward=false and a Limit, avoiding full-table scans and returning top players in sorted order. Option D is correct because DynamoDB Streams can capture score-change events and trigger a Lambda function to maintain a separate materialized leaderboard table, decoupling heavy ranking reads from the high-write base table and improving performance at scale. Option A is not a best practice because Scan reads every item and then requires client-side sorting, which is slow, costly, and does not scale for frequent top-player queries. Option E is not a best practice because using a single partition key for all players concentrates all traffic on one partition, creating a hot partition that throttles throughput and defeats DynamoDB's horizontal scaling.

Answer

Scan the entire table and sort to get top scores

Answer

Use a single partition key for all players to easily query top scores

Question 10

Which TWO AWS services can be used to centrally manage database credentials securely? (Choose two.)

Accepted Answer

AWS Secrets Manager. Options A and E are correct. AWS Secrets Manager is specifically designed to centrally manage secrets, including database credentials, with features like automatic rotation. AWS Systems Manager Parameter Store can also securely store secrets (e.g., using SecureString parameters). Option B (AWS CloudFormation) is incorrect because it is an infrastructure-as-code service, not a secrets manager. Option C (Amazon S3) is incorrect because it is an object storage service, not designed for secret storage. Option D (AWS IAM) is incorrect because it manages access permissions and identities, not secrets.

Answer

AWS CloudFormation

Answer

Amazon S3

Answer

AWS Identity and Access Management (IAM)

Question 11

A company is migrating a 10 TB MongoDB database to Amazon DocumentDB. The migration must have minimal downtime. Which strategy should be used?

Accepted Answer

Use AWS DMS with MongoDB as source and DocumentDB as target, with change data capture.. AWS DMS with MongoDB as source and DocumentDB as target, using change data capture (CDC), is the correct strategy because it enables a live migration with minimal downtime. DMS performs an initial full load of the 10 TB database and then continuously replicates ongoing changes from the MongoDB oplog, allowing you to cut over to DocumentDB with only a brief pause.

Answer

Use mongodump to export the database and mongorestore to import into DocumentDB.

Answer

Use AWS CloudEndure to replicate the MongoDB server to DocumentDB.

Answer

Copy the database files to Amazon S3 and restore to DocumentDB.

Question 12

A company has an Amazon Redshift cluster that contains sensitive data. The security team wants to ensure that all data is encrypted at rest and that the encryption keys are managed by AWS. Which configuration should be used?

Accepted Answer

Enable encryption at rest using the default AWS-managed KMS key for Redshift.. Amazon Redshift supports encryption at rest using AWS KMS. When you enable encryption, you can choose to use the default AWS-managed key (aws/redshift) or a customer-managed key. The default key is managed by AWS, meeting the requirement that keys are managed by AWS. Option A is incorrect because CloudHSM is used for customer-managed keys, not AWS-managed keys. Option B is incorrect because SSE-S3 is for S3 objects, not Redshift clusters. Option D is incorrect because client-side encryption is not supported for Redshift at rest.

Answer

Use AWS CloudHSM to generate and store encryption keys.

Answer

Use server-side encryption with S3-managed keys (SSE-S3) for the Redshift cluster.

Answer

Use client-side encryption with the AWS Encryption SDK.

Question 13

A company is using Amazon Aurora MySQL and needs to audit database logins. Which of the following can be used to capture login events? (Choose TWO.)

Accepted Answer

Database Activity Streams. Options B and E are correct. Database Activity Streams (DAS) in Amazon Aurora capture login events and other database activities. Additionally, the Aurora MySQL audit plugin can be enabled to log connections, including login attempts. Option A (VPC Flow Logs) captures network traffic, not database logins. Option C (Enhanced Monitoring) captures OS-level metrics from the database host. Option D (AWS CloudTrail) records API calls made to AWS services, not database-level events.

Answer

VPC Flow Logs

Answer

Enhanced Monitoring

Answer

AWS CloudTrail

Question 14

A database administrator notices that an Amazon RDS for Oracle instance has a high number of connections, causing performance degradation. Which tool can be used to identify the active sessions and their queries?

Accepted Answer

Performance Insights. Performance Insights provides a dashboard to monitor active sessions and the queries they are running. Option A is incorrect because Amazon Inspector is a security assessment tool, not a monitoring tool for database sessions. Option C is incorrect because RDS Enhanced Monitoring provides OS-level metrics like CPU and memory, not database session details. Option D is incorrect because AWS CloudTrail logs API calls, not database sessions or queries.

Answer

Amazon Inspector

Answer

RDS Enhanced Monitoring

Answer

AWS CloudTrail

Question 15

A company is migrating a 500 GB on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The migration must have minimal downtime and support ongoing replication after the initial load. The network link has limited bandwidth, and the company wants to avoid costly data transfer fees. Which approach should be used?

Accepted Answer

Use AWS DMS with ongoing replication (CDC) from the start.. AWS DMS with ongoing replication (CDC) enables a full load followed by continuous change data capture, which meets the requirements of minimal downtime and ongoing replication. DMS compresses data in transit and can throttle network usage, helping to manage limited bandwidth and avoid costly data transfer fees by using the existing network link efficiently.

Answer

Use AWS Database Migration Service (DMS) with a full load only, then cut over.

Answer

Use pg_dump to export the database and pg_restore to import into RDS.

Answer

Use AWS Snowball Edge to transfer the database files, then load into RDS.