DBS-C01 Management and Operations Practice Test 14 — 15 Questions

Question 1

A company is running an Amazon RDS for MySQL DB instance with Multi-AZ deployment. The database experiences a failover due to a hardware failure. After the failover, the application team reports that a critical stored procedure is missing. What should the database administrator do to prevent this issue in the future?

Accepted Answer

Ensure that the stored procedure is created on both the primary and standby instances by using a script or manually recreating it after failover.. Option D is correct because the default_db_character_set and default_collation_for_utf8 are not the cause; the stored procedure is missing because it was created on the primary and not replicated. Using a custom DB parameter group does not replicate stored procedures; they are stored in the database and should be replicated via binlog. Stored procedures are not automatically replicated in RDS MySQL; the best practice is to ensure they are created on both instances or use a script to recreate them after failover. Option A is incorrect because modifying the DB parameter group does not replicate stored procedures. Option B is incorrect because binlog retention does not affect stored procedure replication. Option C is incorrect because creating the stored procedure as a function does not change replication behavior.

Answer

Create the stored procedure as a function instead.

Answer

Modify the DB parameter group to enable binary logging.

Answer

Increase the binlog retention period to ensure the stored procedure is captured.

Question 2

A company is using Amazon DynamoDB with on-demand capacity mode. The application experiences occasional throttling on a table during peak hours. The table's read and write requests are within the throughput limits, but the provisioned read/write capacity is exceeded. What is the most likely cause of this throttling?

Accepted Answer

The table's previous peak throughput was lower than the current traffic, and DynamoDB is still adapting.. Option B is correct because on-demand capacity mode automatically scales to handle up to the table's previous peak throughput, but it can throttle if there is a sudden spike beyond that peak. Option A is incorrect because on-demand capacity mode does not use provisioned capacity; it scales automatically. Option C is incorrect because partition hot spots can cause throttling even if total throughput is within limits, but the question states that read and write requests are within limits. Option D is incorrect because on-demand capacity mode does not have a table-wide throughput limit; it scales automatically.

Answer

The table has a hot partition that is receiving more requests than the partition can handle.

Answer

The table has exceeded the maximum allowed throughput for on-demand capacity mode.

Answer

The table's provisioned read/write capacity is set too low.

Question 3

A database administrator is monitoring Amazon RDS for PostgreSQL using CloudWatch. The DB instance shows high CPU utilization, but the number of connections is normal. What is the most likely cause of the high CPU utilization?

Accepted Answer

There are long-running queries or missing indexes causing high CPU usage.. Option B is correct because high CPU utilization with normal connections often indicates inefficient queries or missing indexes causing full table scans. Option A is incorrect because burst balance is for gp2 storage, not CPU. Option C is incorrect because insufficient memory usually causes swapping, not high CPU. Option D is incorrect because ReadReplicas do not affect CPU on the primary instance.

Answer

The DB instance has a low burst balance for gp2 storage.

Answer

The instance is low on memory and is swapping.

Answer

The DB instance has a large number of Read Replicas.

Question 4

A company is using Amazon Redshift for data warehousing. They notice that query performance has degraded over time. The database administrator checks the system tables and finds that there is significant skew in data distribution across slices. What action should be taken to improve query performance?

Accepted Answer

Recreate the table with a different distribution style, such as KEY distribution on a column with high cardinality.. Option D is correct because data skew causes some slices to have more data than others, leading to slower queries. Recreating the table with a different distribution style can help. Option A is incorrect because vacuum reclaims space and analyzes statistics, but does not fix data skew. Option B is incorrect because modifying sort keys can improve query performance but does not address data skew. Option C is incorrect because adding more nodes does not automatically redistribute existing data; skew persists.

Answer

Increase the number of nodes in the cluster.

Answer

Run the VACUUM command to reclaim space and update statistics.

Answer

Modify the sort keys to better match the query patterns.

Question 5

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.. Option A is correct because 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 enabling Multi-AZ adds a standby but does not increase write IOPS capacity on the primary. Option C is incorrect because increasing the storage size may increase IOPS if using gp2 but not necessarily, and the issue is IOPS, not storage capacity. Option D is incorrect because the instance class is already optimized for memory; the issue is I/O, not memory.

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 6

A company uses Amazon DynamoDB with provisioned capacity. The application team reports occasional ProvisionedThroughputExceededException errors. The database administrator notices that the errors occur during periods of high traffic. What is the most cost-effective way to handle these errors without over-provisioning capacity?

Accepted Answer

Implement exponential backoff and retry logic in the application.. Option D is correct because implementing exponential backoff with retries handles throttling errors gracefully without over-provisioning. Option A is incorrect because it is costly and inefficient to over-provision. Option B is incorrect because DynamoDB Accelerator (DAX) is a cache, but it does not increase write capacity; it can reduce read load but not write throttling. Option C is incorrect because switching to on-demand may be more cost-effective for spiky traffic, but it is not the most cost-effective if traffic is predictable; the question asks for most cost-effective.

Answer

Increase the provisioned read and write capacity to the peak traffic level.

Answer

Use DynamoDB Accelerator (DAX) to cache frequently accessed items.

Answer

Switch to on-demand capacity mode.

Question 7

A company is running an Amazon RDS for SQL Server DB instance. The database administrator needs to perform a major version upgrade. What is the recommended approach to minimize downtime?

Accepted Answer

Create a Read Replica of the DB instance with the new version, promote it to a standalone instance, and then redirect application traffic.. Option C is correct because creating a Read Replica with the new version, promoting it, and then redirecting traffic minimizes downtime. Option A is incorrect because modifying the DB instance directly causes downtime during the upgrade. Option B is incorrect because taking a snapshot and restoring takes time and causes downtime. Option D is incorrect because AWS DMS can migrate with minimal downtime, but it is more complex and not the standard recommended approach for version upgrades.

Answer

Use AWS Database Migration Service (DMS) to migrate the database to a new instance with the new version.

Answer

Take a snapshot of the DB instance and restore it with the new version.

Answer

Modify the DB instance directly and apply the new version during the maintenance window.

Question 8

A company is using Amazon Aurora MySQL-Compatible Edition. The database administrator notices that the Aurora cluster has a high number of binary log (binlog) files in the cluster volume, consuming significant storage. The binlog retention period is set to 24 hours. What is the most efficient way to reduce the storage consumed by binlog files without compromising point-in-time recovery (PITR)?

Accepted Answer

Disable binary logging on the Aurora cluster by setting the binlog_format parameter to OFF.. Option D is correct because Aurora MySQL does not rely on binlogs for PITR; it uses its own storage-based recovery. Disabling binlog altogether saves storage and reduces I/O. Option A is incorrect because reducing the retention period may not be sufficient if binlogs are still accumulating. Option B is incorrect because binlog files are not stored on the DB instance but in the cluster volume; deleting them manually is not recommended. Option C is incorrect because using the Binary Log Export feature is for exporting logs, not reducing storage.

Answer

Manually delete binlog files from the DB instance using the 'PURGE BINARY LOGS' command.

Answer

Use the 'Binary Log Export' feature to export binlogs to Amazon S3 and delete them from the cluster.

Answer

Reduce the binlog retention period to 1 hour.

Question 9

A company is using Amazon DynamoDB with global tables. The application writes to a table in the us-east-1 region. The database administrator notices that updates made in us-east-1 are not appearing in the replica table in eu-west-1. What is the most likely cause?

Accepted Answer

DynamoDB Streams are not enabled on the table.. Option C is correct because global tables rely on DynamoDB Streams to replicate changes. If streams are disabled, replication stops. Option A is incorrect because DynamoDB does not have a replication delay setting. Option B is incorrect because IAM permissions would cause errors, not silent failure. Option D is incorrect because point-in-time recovery does not affect replication.

Answer

The replication delay is set too high.

Answer

Point-in-time recovery is not enabled on the replica table.

Answer

The IAM role for replication does not have sufficient permissions.

Question 10

A company is using Amazon RDS for PostgreSQL with Multi-AZ deployment. The database administrator needs to perform a minor version upgrade with minimal downtime. Which TWO actions should the administrator take? (Choose TWO.)

Accepted Answer

Test the upgrade on a separate non-production environment first.. Options A and D are correct. Performing the upgrade during the maintenance window allows RDS to handle the upgrade automatically with a failover, minimizing downtime. Testing the upgrade on a non-production environment first is a best practice to ensure compatibility. Option B is incorrect because taking a snapshot before upgrade is a good practice but does not reduce downtime. Option C is incorrect because disabling Multi-AZ would cause downtime during the upgrade. Option E is incorrect because modifying the DB parameter group is not required for minor version upgrades.

Answer

Disable Multi-AZ before the upgrade to reduce complexity.

Answer

Modify the DB parameter group to set the new version parameters.

Answer

Take a snapshot of the DB instance before the upgrade.

Question 11

A company is using Amazon DynamoDB with on-demand capacity mode. The application experiences occasional throttling during traffic spikes. The database administrator wants to implement a solution to reduce throttling. Which THREE actions should the administrator take? (Choose THREE.)

Accepted Answer

Use DynamoDB Accelerator (DAX) to cache frequently accessed items.. Options A, C, and D are correct. Implementing retry logic with exponential backoff handles throttling gracefully. Using DynamoDB Accelerator (DAX) reduces read load on the table, which can help with read throttling. Designing the application to handle throttling by retrying ensures resilience. Option B is incorrect because switching to provisioned capacity may not be cost-effective and does not inherently reduce throttling. Option E is incorrect because enabling auto scaling is not applicable to on-demand mode.

Answer

Enable auto scaling for the table.

Answer

Switch the table to provisioned capacity mode with auto scaling.

Question 12

A company is using Amazon Redshift for data warehousing. The database administrator needs to optimize query performance. Which TWO actions should the administrator take? (Choose TWO.)

Accepted Answer

Analyze the tables to update statistics for the query optimizer.. Options B and D are correct. Running VACUUM reclaims space and re-sorts data, improving performance. Analyzing tables updates statistics for the query optimizer. Option A is incorrect because increasing the number of nodes improves performance but is not an optimization action; it's a scaling action. Option C is incorrect because disabling compression reduces performance. Option E is incorrect because enabling encryption does not directly affect query performance.

Answer

Increase the number of nodes in the cluster.

Answer

Enable encryption for the cluster.

Answer

Disable compression on the tables to reduce CPU overhead.

Question 13

Refer to the exhibit. A database administrator runs the AWS CLI command to check the status of an Amazon RDS MySQL DB instance. Based on the output, what action is required to apply the pending modifications?

Accepted Answer

Reboot the DB instance to apply the pending parameter group changes.. Option C is correct because the ParameterApplyStatus is 'pending-reboot', indicating that a reboot is required to apply the parameter changes. The backup window change and password update are also pending, but the parameter group changes specifically require a reboot. Option A is incorrect because modifying the backup window does not require a reboot. Option B is incorrect because modifying the DB parameter group is already done; the status shows pending-reboot. Option D is incorrect because a snapshot is not required to apply changes.

Answer

Take a snapshot of the DB instance before applying changes.

Answer

Modify the DB parameter group to change the parameter values.

Answer

Modify the DB instance to set the backup retention period to 7.

Question 14

Refer to the exhibit. A database administrator is writing an IAM policy to manage Amazon RDS snapshots. The policy allows actions on all RDS resources but denies deletion of any DB instance with the prefix 'production-'. A developer attempts to delete a snapshot named 'production-snapshot-2020'. Will this action be allowed?

Accepted Answer

Yes, because the Deny statement only applies to deleting DB instances, not snapshots.. Option B is correct because the 'Deny' statement only applies to the 'rds:DeleteDBInstance' action, not to 'rds:DeleteDBSnapshot'. The 'Allow' statement explicitly allows 'rds:DeleteDBSnapshot' on all resources. Since there is no explicit deny for deleting snapshots, the allow takes effect. Option A is incorrect because the deny only applies to deleting instances, not snapshots. Option C is incorrect because the policy does not deny snapshot deletion. Option D is incorrect because the developer is allowed to delete snapshots.

Answer

Yes, but only if the developer has the necessary permissions.

Answer

No, because the Deny statement overrides the Allow statement.

Answer

No, because the snapshot name starts with 'production-', which matches the resource pattern in the Deny statement.

Question 15

Refer to the exhibit. A database administrator runs the AWS CLI command to retrieve CloudWatch metrics for an Amazon RDS DB instance. The output shows a spike in WriteLatency at 10:05 UTC. What is the most likely cause of this spike?

Accepted Answer

The DB instance's gp2 volume has exhausted its burst credits.. Option A is correct because a sudden spike in write latency often indicates that the storage volume has exhausted its burst credits and is now using baseline performance, which may be slower. Option B is incorrect because a large number of connections typically causes increased CPU and memory usage, not necessarily a latency spike. Option C is incorrect because a Multi-AZ failover would cause a brief downtime, not a latency spike. Option D is incorrect because a snapshot would cause I/O suspension, not a latency spike.

Answer

The DB instance is in the process of taking a snapshot.

Answer

There is a large number of concurrent connections to the DB instance.

Answer

The DB instance experienced a Multi-AZ failover.