DBS-C01 Management and Operations Practice Test 7 — 15 Questions

Question 1

A database administrator is troubleshooting a performance issue on an Amazon RDS for SQL Server instance. The CPU utilization is consistently above 90%, and the number of database connections is high. Which Amazon CloudWatch metric should be analyzed first to determine if the issue is due to a specific query?

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

Accepted Answer

Enhanced Monitoring (cpuUtilization per process). Enhanced Monitoring provides per-process CPU utilization metrics, which allow you to identify if a specific SQL Server query or session is consuming excessive CPU. Unlike aggregate metrics like CPUUtilization, Enhanced Monitoring breaks down CPU usage by process (e.g., sqlservr.exe), enabling you to pinpoint a problematic query. This is the most direct way to determine if the high CPU is driven by a specific query rather than general load.

Answer

DatabaseConnections

Answer

ReadIOPS

Answer

CPUUtilization

Question 2

A company has an Amazon RDS for MySQL DB instance that is running low on storage. The current allocated storage is 500 GB, and the free space is down to 10 GB. The database administrator wants to increase storage with minimal downtime. Which action should be taken?

Accepted Answer

Use the AWS Management Console to modify the DB instance and increase the allocated storage.. RDS supports modifying storage online with minimal downtime. Increasing allocated storage from 500 GB to, for example, 600 GB can be done via a modification to the DB instance. The instance remains available during the modification, though a brief performance impact may occur. Stopping the instance is unnecessary. Creating a snapshot and restoring would cause longer downtime. Waiting for autoscaling might not be quick enough if space is critically low.

Answer

Stop the DB instance, modify the allocated storage, and start the instance.

Answer

Create a snapshot of the current DB instance, restore it to a new larger instance, and point the application to the new endpoint.

Answer

Enable storage autoscaling and wait for the automatic increase.

Question 3

A company uses Amazon DynamoDB with on-demand capacity mode for a critical application. During a marketing campaign, the application experienced throttled requests despite the on-demand mode. The table has a single partition key. The database specialist notices that the throttling occurs sporadically even though overall traffic is within limits. What is the most likely cause?

Accepted Answer

The table's partition key is causing a hot partition, leading to throttling on that partition.. On-demand mode accommodates traffic spikes, but if a single partition key is used, all traffic goes to one partition. DynamoDB partitions data by partition key; a single hot key can throttle requests even if overall throughput is within limits. Provisioned capacity is not used. Auto scaling is not relevant. The partition limit is a hard limit.

Answer

The table's provisioned capacity is set too low.

Answer

The table's auto scaling is not configured correctly.

Answer

The application is exceeding the DynamoDB account-level throughput limits.

Question 4

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size. The company wants to minimize downtime during the migration. Which AWS service should be used to perform an online migration with minimal downtime?

Accepted Answer

AWS Database Migration Service (DMS). AWS Database Migration Service (DMS) supports ongoing replication to minimize downtime. Snowball is for offline data transfer. S3 is not a migration service. Direct Connect provides a dedicated network connection but is not a migration service itself.

Answer

AWS Direct Connect

Answer

AWS Snowball

Answer

Amazon S3

Question 5

A database administrator needs to retain backups of an Amazon RDS for PostgreSQL DB instance for 7 years to meet compliance requirements. The automated backup retention period is limited to 35 days. Which solution should be used?

Accepted Answer

Create manual snapshots at regular intervals and retain them for 7 years.. Manual snapshots are retained indefinitely until deleted. Automated backups have a max retention of 35 days. Exporting to S3 is an option but not directly a backup retention method; you can export snapshots to S3, but manual snapshots are the standard way to retain backups long-term. EC2 instance backups are not applicable.

Answer

Export the automated backups to Amazon S3 and apply an S3 lifecycle policy.

Answer

Increase the automated backup retention period to 7 years.

Answer

Use an AWS Lambda function to copy automated backups to an EC2 instance.

Question 6

A company is running a production Amazon RDS for MySQL Multi-AZ DB instance. The database administrator needs to perform a minor version upgrade with minimal downtime. Which TWO actions should be taken? (Choose TWO.)

Accepted Answer

Modify the DB instance to enable automatic minor version upgrade.. Enabling automatic minor version upgrades on an RDS for MySQL Multi-AZ instance allows Amazon RDS to apply the upgrade during the next maintenance window with minimal downtime. During the upgrade, RDS patches the standby first, then performs a failover to make the standby the new primary, resulting in a brief (typically under 60 seconds) interruption rather than a full outage. This approach leverages the Multi-AZ architecture to reduce downtime compared to manual upgrades.

Answer

Create a read replica, upgrade the replica, and promote it.

Answer

Modify the DB instance to be a Single-AZ deployment to simplify the upgrade.

Answer

Stop the DB instance before applying the upgrade.

Question 7

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 8

A company is using Amazon RDS for MariaDB. The database administrator wants to monitor the database for slow queries. Which TWO services can be used to achieve this? (Choose TWO.)

Accepted Answer

Amazon RDS Performance Insights. Amazon RDS Performance Insights (Option A) is correct because it provides a database performance tuning and monitoring feature that visualizes database load and allows you to identify and analyze slow queries by filtering on SQL statements, waits, and hosts. Amazon CloudWatch Logs (Option C) is correct because you can enable the slow query log for MariaDB and publish those logs to CloudWatch Logs, then use CloudWatch Logs Insights to query and filter for slow queries based on execution time.

Answer

AWS Config

Answer

Amazon RDS Enhanced Monitoring

Answer

AWS CloudTrail

Question 9

A company is running a production Amazon RDS for MySQL DB instance. The database size is 500 GB and the workload is write-heavy. The team notices that the automated backups are taking longer than expected and are impacting the performance during the backup window. Which action should be taken to minimize the performance impact?

Accepted Answer

Create a read replica and configure automated backups on the replica.. Creating a read replica and configuring automated backups on the replica offloads the backup process from the primary DB instance. Since the workload is write-heavy, this minimizes the performance impact on the primary during the backup window. Option A is incorrect because disabling automated backups removes the ability to perform point-in-time recovery, which is risky for a production database. Option C is incorrect because increasing the DB instance size may improve backup speed but does not eliminate the performance impact on the primary instance, and it adds unnecessary cost. Option D is incorrect because moving the backup window to a low workload time does not reduce the performance impact during that window; it only changes when the impact occurs, and the workload may still be significant.

Answer

Disable automated backups and rely on manual snapshots taken during off-peak hours.

Answer

Increase the DB instance size to improve backup performance.

Answer

Move the backup window to a time when the workload is lowest.

Question 10

A company is using Amazon Aurora MySQL-Compatible Edition. The database has frequent deadlocks, and the application team suspects that the isolation level is causing the issue. The current isolation level is REPEATABLE READ. The team wants to reduce deadlocks while maintaining data consistency. Which isolation level should be recommended?

Accepted Answer

READ COMMITTED. (READ COMMITTED) is correct because it reduces locking compared to REPEATABLE READ, which helps minimize deadlocks in high-concurrency environments. In READ COMMITTED, MySQL uses row-level locks only for the duration of the statement, not the entire transaction, reducing the chance of deadlocks. It still provides consistent reads at the statement level, avoiding dirty reads. Option A (READ UNCOMMITTED) is wrong because it allows dirty reads and is not suitable for transactional consistency. Option C (SNAPSHOT ISOLATION) is wrong because it is not supported by MySQL; it is a SQL Server feature. Option D (SERIALIZABLE) is wrong because it increases locking, leading to more deadlocks.

Answer

READ UNCOMMITTED

Answer

SNAPSHOT ISOLATION

Answer

SERIALIZABLE

Question 11

A company has an Amazon DynamoDB table that stores session data for a web application. The table's read capacity units (RCUs) are consistently near 100% utilization during peak hours, causing throttling. The application can tolerate eventually consistent reads. Which action should the application team take to reduce throttling?

Accepted Answer

Change the read consistency to eventually consistent.. Eventually consistent reads consume only half the Read Capacity Units (RCUs) compared to strongly consistent reads. Switching to eventually consistent reads effectively doubles the read capacity, reducing throttling without additional cost. Option A is incorrect because decreasing provisioned RCUs would reduce capacity and worsen throttling. Option B is incorrect because while DAX can cache session data and reduce read load on the table, it does not directly address the RCU consumption for reads that still hit the table; moreover, implementing DAX adds complexity and cost. Option D is incorrect because increasing RCUs would solve throttling but at a higher cost, whereas eventually consistent reads provide a cost-effective solution.

Answer

Decrease the provisioned RCUs for the table.

Answer

Enable DynamoDB Accelerator (DAX) to cache the session data.

Answer

Increase the provisioned RCUs for the table.

Question 12

A database administrator is troubleshooting a performance issue on an Amazon RDS for SQL Server instance. The CPU utilization is consistently above 90%, and the number of database connections is high. Which Amazon CloudWatch metric should be analyzed first to determine if the issue is due to a specific query?

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

Accepted Answer

The query is expected to return a large percentage of rows.. When a query is expected to return a large percentage of rows, a sequential scan is often more efficient than an index scan due to the overhead of random I/O from the index. Option B is wrong because the scenario includes a WHERE clause, so SELECT * without WHERE does not apply. Option C is wrong because outdated statistics could cause the optimizer to choose a sequential scan, but the question asks for a reason the planner might choose sequential scan; outdated stats are a possible cause but not the direct reason given in A. Option D is wrong because the index order does not automatically force its use; the optimizer decides based on selectivity.

Answer

The query is a SELECT * without a WHERE clause.

Answer

The table's statistics are outdated.

Answer

The index on the column is not being used because it is a composite index with a different column order.

Question 13

A company is migrating an on-premises Oracle database to Amazon Aurora PostgreSQL. The database has several stored procedures that use Oracle-specific PL/SQL. The team needs to minimize manual code changes. Which AWS service or tool should be used to automate the conversion of the stored procedures?

Accepted Answer

AWS Schema Conversion Tool (AWS SCT). The AWS Schema Conversion Tool (AWS SCT) is the correct choice because it automates the conversion of Oracle PL/SQL stored procedures to PostgreSQL PL/pgSQL, minimizing manual code changes. Option B (Amazon Aurora PostgreSQL native compatibility) does not automatically convert Oracle PL/SQL; it only supports some PostgreSQL features. Option C (AWS DMS) handles data migration, not schema or code conversion. Option D (manual rewrite) is not automated and contradicts the requirement to minimize manual changes.

Answer

Amazon Aurora PostgreSQL native compatibility

Answer

AWS Database Migration Service (AWS DMS)

Answer

Manual rewrite using PostgreSQL PL/pgSQL

Question 14

An application is experiencing increased latency when writing to an Amazon DynamoDB table. The table uses on-demand capacity mode. The CloudWatch metric 'WriteThrottleEvents' is zero. What is the most likely cause of the increased latency?

Accepted Answer

A hot partition is causing excessive write traffic to a single partition.. On-demand DynamoDB tables can experience throttling if you exceed the previous peak traffic by more than double in a short time, but since WriteThrottleEvents is zero, the latency is likely due to a hot partition causing uneven traffic distribution. Option A is incorrect because on-demand capacity does not use WCUs; throughput is automatically scaled. Option B is incorrect because DynamoDB Accelerator (DAX) is a read cache and does not affect write latency. Option D is incorrect because on-demand tables do not have provisioned capacity; throttling would be indicated by WriteThrottleEvents, which is zero.

Answer

The write capacity units (WCUs) are set too low.

Answer

DynamoDB Accelerator (DAX) is not configured for writes.

Answer

The table is experiencing write throttling due to exceeding the provisioned write capacity.

Question 15

A company is running an Amazon RDS for SQL Server Multi-AZ DB instance. During a recent failover test, the application experienced a timeout of 60 seconds. The application uses a connection string that points to the CNAME of the DB instance. Which configuration change would reduce the failover time?

Accepted Answer

Enable TDS Keep-Alive on the client side to detect and recover from connection drops faster.. Enable TDS Keep-Alive on the client side. This allows the client to detect connection drops faster and reconnect to the new primary during failover, reducing the timeout experienced. Option A (Create a read replica and promote it) is a manual process and does not reduce failover time; it is used for read scaling or disaster recovery. Option B (Using the IP address) is not recommended because the IP changes after failover; the CNAME automatically updates to point to the new primary, so using IP would cause longer outages. Option D (Disable Multi-AZ) would eliminate automatic failover, increasing downtime during failures.

Answer

Create a read replica and promote it to a standalone instance during failover.

Answer

Modify the application to use the IP address of the DB instance instead of the CNAME.

Answer

Disable Multi-AZ and use a single-AZ instance to avoid failover overhead.