DBS-C01 Management and Operations Practice Test 12 — 15 Questions

Question 1

A company has an Amazon DynamoDB table with on-demand capacity mode. The table experiences occasional spikes in traffic. During these spikes, some requests receive ProvisionedThroughputExceededException errors. The company wants to minimize these errors without changing the application. Which solution should be used?

Accepted Answer

Switch the table to provisioned capacity mode and enable auto scaling.. On-demand mode automatically scales to handle traffic spikes, but there is a per-partition throughput limit. Using DynamoDB Accelerator (DAX) caches responses and reduces read load, but for write spikes, it does not help. Switching to provisioned capacity with auto scaling can handle spikes if configured correctly, but on-demand should already handle spikes. However, the errors indicate that the per-partition throughput limit is being exceeded. The best solution is to enable auto scaling with provisioned capacity to handle bursts better than on-demand? Actually, on-demand is supposed to handle spikes, but there is a per-partition limit. The best answer is to use DynamoDB global tables to distribute load. But among options, B (switch to provisioned capacity with auto scaling) is often recommended for predictable spikes. Option A (increase read/write capacity units) is not applicable for on-demand; Option C (DAX) does not help write errors; Option D (global tables) helps with disaster recovery, not throughput. So B is correct.

Answer

Enable DynamoDB Accelerator (DAX) for caching.

Answer

Increase the read and write capacity units manually.

Answer

Use DynamoDB global tables to distribute the load across multiple regions.

Question 2

A company runs an Amazon RDS for SQL Server DB instance in a VPC. The security group for the DB instance allows inbound traffic on port 1433 from the application servers' security group. The application servers can connect to the database, but a database administrator cannot connect from their workstation using SQL Server Management Studio (SSMS). What is the MOST likely cause?

Accepted Answer

The security group does not allow inbound traffic from the DBA workstation's IP address.. The DBA's workstation is not within the VPC, so it needs a public IP and the security group must allow inbound traffic from the workstation's IP. Option A (DBA's IP not in security group) is correct. Option B (SSMS version) is unlikely; Option C (Multi-AZ) irrelevant; Option D (encryption) does not prevent connection.

Answer

The DBA is using an incompatible version of SSMS.

Answer

The DB instance is configured as Multi-AZ, which restricts direct connections.

Answer

The DB instance has encryption enabled, which blocks non-encrypted connections.

Question 3

A company uses Amazon DynamoDB with global tables in a multi-Region active-active configuration. The application writes to the table in us-east-1 and reads from us-west-2. Recently, a network partition occurred between the two regions, and after recovery, some data was lost. What is the most likely reason for the data loss?

Accepted Answer

The last-writer-wins conflict resolution used timestamp-based coordination without clock synchronization.. Global tables use last-writer-wins (LWW) conflict resolution based on timestamps. If clocks are not synchronized, an older write from one region can overwrite a newer write. Option A (network partition caused inconsistent replication) is not the direct cause; Option B (LWW with unsynchronized clocks) is correct. Option C (Consistent Reads) is unrelated; Option D (TTL) is not relevant.

Answer

The application used eventually consistent reads, causing stale data to be overwritten.

Answer

The table had a TTL attribute that expired the data before replication completed.

Answer

The network partition caused the replication to stop, and data was not replicated.

Question 4

A database administrator notices that an Amazon RDS for MySQL DB instance has experienced a failover during a maintenance window. What is the most likely cause of this failover?

Accepted Answer

A system update was applied during the maintenance window, causing a reboot. Option C is correct because the RDS maintenance window is used to apply system updates, which may require a reboot and failover if Multi-AZ is enabled. Option A is wrong because manual failover is initiated by the administrator. Option B is wrong because storage scaling does not cause failover. Option D is wrong because read replica creation does not cause failover.

Answer

The DB instance ran out of storage and automatically failed over

Answer

A read replica was promoted to a primary instance

Answer

A manual failover was initiated by the administrator

Question 5

A company runs an Amazon RDS for PostgreSQL DB instance with Multi-AZ enabled. The primary instance is in us-east-1a and the standby is in us-east-1b. During a routine audit, the security team discovers that database connections are being terminated unexpectedly. The database administrator reviews the RDS events and sees an event: 'A Multi-AZ failover has been completed.' What step should be taken to determine the cause of this failover?

Accepted Answer

Review RDS events and AWS CloudTrail logs for API calls related to the failover. Option B is correct because RDS events and CloudTrail logs provide detailed information about failover causes. Option A is wrong because the RDS console shows events but not detailed causes. Option C is wrong because CloudWatch metrics show performance but not failover reasons. Option D is wrong because the RDS API describes instances, not failover causes.

Answer

Examine Amazon CloudWatch metrics for increased CPU or memory usage

Answer

Check the RDS console for maintenance windows

Answer

Run the describe-db-instances CLI command to check the status of the standby

Question 6

A database team is migrating an on-premises Oracle database to Amazon Aurora PostgreSQL. The team needs to ensure minimal downtime and data consistency. Which approach should be used?

Accepted Answer

Use AWS Database Migration Service (DMS) with ongoing replication using change data capture (CDC). AWS DMS with ongoing replication using change data capture (CDC) is the correct approach because it enables a live migration with minimal downtime. DMS can perform a full load of the Oracle database and then continuously replicate ongoing changes from Oracle to Aurora PostgreSQL, ensuring data consistency at the point of cutover. This method avoids the need for a long maintenance window and supports heterogeneous migrations with automatic schema conversion.

Answer

Use the PostgreSQL foreign data wrapper (FDW) to link the Oracle database

Answer

Use AWS Server Migration Service (SMS) to replicate the database

Answer

Use pg_dump and pg_restore to migrate the data during a maintenance window

Question 7

A company has an Amazon DynamoDB table with on-demand capacity mode. The table experiences a sudden spike in traffic, and the application starts receiving ProvisionedThroughputExceededException errors. What is the most likely cause?

Accepted Answer

The traffic spike exceeded the previous peak traffic by more than double in a short period. Option D is correct because on-demand mode can throttle if traffic exceeds the previous peak by a large margin in a short time. Option A is wrong because on-demand mode does not have provisioned throughput. Option B is wrong because there is no auto-scaling in on-demand mode. Option C is wrong because read/write capacity units are not set.

Answer

The provisioned read capacity units are insufficient

Answer

The table has reached the maximum number of read capacity units

Answer

Auto Scaling is not configured to increase capacity

Question 8

A company is using Amazon RDS for SQL Server with Multi-AZ and automated backups enabled. The database administrator needs to restore the database to a specific point in time that is within the retention period. What is the correct procedure?

Accepted Answer

Use the RDS console to perform a point-in-time recovery to the desired time. Option B is correct because point-in-time recovery is performed through the RDS console or API by specifying the time. Option A is wrong because it restores the latest backup. Option C is wrong because it restores a manual snapshot. Option D is wrong because automated backups are used for point-in-time recovery.

Answer

Restore from a manual snapshot taken at the desired time

Answer

Use the native SQL Server backup and restore functionality

Answer

Restore from the latest automated snapshot

Question 9

An Amazon RDS for MySQL DB instance has a high number of connections and the application is experiencing slow response times. The database administrator wants to identify the queries that are causing the most load. Which approach is most effective?

Accepted Answer

Enable Amazon RDS Performance Insights and review the top SQL queries. Option C is correct because Performance Insights provides a dashboard to identify top queries by load. Option A is wrong because it shows connections, not query performance. Option B is wrong because CloudWatch logs show slow queries but not in real-time. Option D is wrong because RDS events show instance events, not query load.

Answer

Enable slow query logs and analyze them in CloudWatch Logs

Answer

Monitor the DatabaseConnections metric in CloudWatch

Answer

Check RDS events for any error messages

Question 10

A company is using Amazon DynamoDB with global tables (multi-region) for a gaming application. The application writes to a table in us-east-1 and reads from a table in eu-west-1. The team notices that writes in us-east-1 are taking longer than expected to propagate to eu-west-1. What is the most likely cause?

Accepted Answer

Network latency between the regions is causing replication delay. Option D is correct because global tables eventually replicate asynchronously; network latency between regions can cause delays. Option A is wrong because conflict resolution does not cause delays. Option B is wrong because throughput is separate per region. Option C is wrong because Streams are used for replication, not the cause of delay.

Answer

The write capacity in eu-west-1 is insufficient

Answer

Conflicts are being resolved due to concurrent writes

Answer

DynamoDB Streams is disabled on the table

Question 11

A company is using Amazon ElastiCache for Redis to cache database query results. The application team reports that cache hit ratio has dropped significantly. What is the first step to investigate?

Accepted Answer

Check the CacheHitRate and Evictions metrics in CloudWatch. When the cache hit ratio drops significantly, the first step is to investigate whether the cache is evicting keys due to memory pressure or if the working set no longer fits. CloudWatch metrics such as `CacheHitRate` and `Evictions` provide immediate visibility into these conditions without requiring direct Redis access. This aligns with the AWS Well-Architected Framework's principle of observability before making configuration changes.

Answer

Run the Redis INFO command to see memory usage

Answer

Review the ElastiCache event logs for node failures

Answer

Check the Redis AOF persistence logs

Question 12

An Amazon RDS for Oracle DB instance is experiencing high swap usage. The database administrator wants to reduce swap usage. Which action should be taken?

Accepted Answer

Increase the DB instance class to a larger size with more memory. High swap usage on an Amazon RDS for Oracle DB instance indicates that the operating system is using disk-based swap space as a substitute for physical RAM, which severely degrades database performance. Increasing the DB instance class to a larger size with more memory directly addresses the root cause by providing additional RAM, reducing or eliminating the need for swapping. This is the correct action because swap usage is a memory pressure issue, not a storage or availability problem.

Answer

Change the storage type from gp2 to io1

Answer

Delete archived redo logs to free up space

Answer

Enable Multi-AZ to distribute the load

Question 13

Which TWO actions can be taken to monitor the health of an Amazon DynamoDB table? (Choose 2.)

Accepted Answer

Enable Amazon CloudWatch metrics for the table. Options A and C are correct. CloudWatch metrics provide health indicators (throttling, latency). DynamoDB Streams can be used to track changes but not health directly. Options B and D are incorrect: B is for data plane, D is for monitoring, but not health.

Answer

Use AWS Trusted Advisor to check table limits

Answer

Enable DynamoDB Streams and process events with AWS Lambda

Answer

Use DynamoDB Accelerator (DAX) to improve response times

Question 14

Which THREE factors should be considered when selecting the backup strategy for an Amazon RDS for PostgreSQL DB instance? (Choose 3.)

Accepted Answer

The backup retention period. Option A is correct because the backup retention period directly determines how far back you can perform a point-in-time recovery (PITR) for an RDS for PostgreSQL instance. Amazon RDS stores automated backups and transaction logs for the specified retention period (1 to 35 days), and this period must be aligned with your compliance and operational requirements. Choosing an appropriate retention period is a fundamental factor in defining the backup strategy.

Answer

The need for Multi-AZ deployment

Answer

The encryption at rest requirement

Question 15

Which TWO methods can be used to reduce the read latency for an Amazon Aurora MySQL database? (Choose 2.)

Accepted Answer

Use Aurora Auto Scaling to add replica capacity based on load. Option B is correct because Aurora Auto Scaling automatically adjusts the number of Aurora Replicas in response to changes in read workload, thereby reducing read latency by distributing read traffic across additional replicas. Option E is correct because adding Aurora Replicas offloads read queries from the primary instance, allowing parallel processing of read requests and reducing contention, which directly lowers read latency.

Answer

Enable encryption at rest

Answer

Increase the write capacity of the DB instance

Answer

Enable Amazon ElastiCache in front of the database