DBS-C01 Management and Operations Practice Test 20 — 15 Questions

Question 1

Refer to the exhibit. A database engineer runs the query above to troubleshoot an application error. The query returns no results even though the database is generating errors. What is the most likely reason?

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

Accepted Answer

The log stream format uses a different field name for the error message. The query filters on the 'message' field, but the log stream format may use a different field name for the error message, such as 'errorMessage' or 'event.message'. Since the query returns no results despite errors existing, the most likely reason is a field name mismatch. Option B is incorrect because the query uses a regex pattern with case-insensitive matching (indicated by the 'i' flag), so case sensitivity is not an issue. Option C is incorrect because queries in CloudWatch Logs Insights default to the last 15 minutes if no time range is specified, so that would not cause zero results if errors are recent. Option D is incorrect because exporting to CloudWatch Logs is not required for querying; the logs are already in CloudWatch Logs.

Answer

The regex pattern does not match because it is case-sensitive

Answer

The query does not specify a time range, so no results are returned

Answer

The log group has not been configured to export to CloudWatch Logs

Question 2

Refer to the exhibit. A database engineer is assigned this IAM policy. Which of the following actions can the engineer perform? (Choose two.)

Accepted Answer

Describe all automated snapshots. The IAM policy includes an Allow statement for 'rds:DescribeDBSnapshots' on all resources, so the engineer can describe any snapshot, including automated snapshots (Option A). It also includes an Allow statement for 'rds:CreateDBSnapshot' on all resources, allowing creation of a manual snapshot with any name, such as 'test-snapshot' (Option E). There is no Allow statement for 'rds:DeleteDBSnapshot', and a Deny statement explicitly blocks deletion of snapshots with names starting with 'prod-'. Therefore, deleting any manual snapshot (Options B, C, D) is not permitted. The correct answers are A and E.

Answer

Delete a manual snapshot named dev-snapshot

Answer

Delete a manual snapshot named prod-database-snapshot

Answer

Delete a manual snapshot named prod-backup

Question 3

Refer to the exhibit. A database engineer runs the command and receives the above output. The engineer wants to convert the database to Multi-AZ. Which command should be used?

Accepted Answer

aws rds modify-db-instance --db-instance-identifier mydb --multi-az. 'aws rds modify-db-instance' with the '--multi-az' flag modifies an existing DB instance to use Multi-AZ deployment. Option A is incorrect because 'reboot-db-instance' with '--force-failover' triggers a reboot and failover but does not change the Multi-AZ setting itself. Option B is incorrect because 'create-db-instance' is used to create a new instance, not modify an existing one. Option D is incorrect because 'create-db-cluster' is for creating an Aurora DB cluster, not for converting a single DB instance to Multi-AZ.

Answer

aws rds reboot-db-instance --db-instance-identifier mydb --force-failover

Answer

aws rds create-db-instance --db-instance-identifier mydb --multi-az

Answer

aws rds create-db-cluster --db-instance-identifier mydb --multi-az

Question 4

A company runs an e-commerce platform using Amazon DynamoDB as the database. The table has a provisioned capacity of 5000 WCU and 3000 RCU. During a flash sale, the write traffic spikes to 8000 WCU for 10 minutes, causing significant throttling. The operations team notices that the table's WriteCapacityUnits metric shows 5000, but the ConsumedWriteCapacityUnits metric peaks at 4500. The application is experiencing errors and slow response times. The team wants to handle such spikes automatically without manual intervention and without over-provisioning. Which solution should be implemented?

Accepted Answer

Enable DynamoDB Auto Scaling with a target utilization of 70% and a minimum capacity of 5000 WCU. DynamoDB Auto Scaling can adjust capacity based on demand, and setting a target utilization of 70% allows headroom for spikes. Option B is wrong because increasing provisioned WCU to 8000 permanently would be costly and result in over-provisioning during normal traffic. Option C is wrong because while SQS can buffer requests, it adds latency and does not solve the real-time throttling issue; it changes the architecture to async processing, which may not be acceptable for an e-commerce platform. Option D is wrong because switching to on-demand capacity mode would handle the spikes automatically but can be significantly more expensive for a workload with a predictable baseline, and the team wants to avoid over-provisioning costs.

Answer

Increase the provisioned WCU to 8000 permanently

Answer

Implement an Amazon SQS queue to buffer write requests and process them asynchronously

Answer

Switch the table to on-demand capacity mode

Question 5

An e-learning platform uses Amazon Aurora MySQL for its database. The application runs reporting queries that scan large portions of the database, causing high CPU utilization on the primary instance. The primary instance is a db.r5.2xlarge with 64 GB memory. The reporting queries are not time-sensitive but need to return results within 5 minutes. The operations team wants to reduce the impact on the primary instance without increasing costs significantly. Which action should be taken?

Accepted Answer

Create an Aurora Replica and configure the reporting application to connect to the replica endpoint. To create an Aurora Replica and direct reporting traffic to it. This offloads the heavy reporting queries from the primary instance, reducing CPU impact without significant cost increase. Aurora Replicas share the same storage and are cost-effective for read-heavy workloads.

Answer

Modify the DB cluster parameter group to enable result set caching

Answer

Use Amazon ElastiCache to cache the reporting results

Answer

Increase the primary instance to db.r5.4xlarge

Question 6

A company uses Amazon RDS for PostgreSQL with a single-AZ deployment. The operations team needs to ensure that the database is available during a planned maintenance event that requires a reboot. The maintenance window is set for 30 minutes. The database size is 200 GB and the application can tolerate a few minutes of downtime. Which action should the team take to minimize downtime during the reboot?

Accepted Answer

Modify the DB instance to be Multi-AZ. Enabling Multi-AZ on the RDS instance creates a standby in a different Availability Zone. During planned maintenance, Amazon RDS automatically performs a failover to the standby, resulting in minimal downtime (typically under a minute), which meets the requirement of a few minutes of downtime. Option A is incorrect because restoring from a manual snapshot takes much longer than a few minutes and is not an automated failover. Option B is incorrect because promoting a read replica requires manual intervention and the replica may not be fully synchronized, leading to potential data loss and longer downtime. Option C merely schedules the reboot during low traffic but does not reduce the downtime of the reboot itself; the instance still becomes unavailable during the reboot.

Answer

Take a manual snapshot before the maintenance window and restore it if needed

Answer

Create a read replica and promote it to primary after the reboot

Answer

Schedule the reboot during a low-traffic period

Question 7

A company is running an Amazon RDS for MySQL Multi-AZ DB instance. The application experiences a brief write disruption during automatic failover. The database workload has low write latency requirements. Which configuration change would minimize application impact during failover?

Accepted Answer

Change the DB instance to use a Multi-AZ DB cluster configuration.. Changing to a Multi-AZ DB cluster (option B) reduces application impact during failover because it uses a writer and two reader instances in separate Availability Zones. Failover to a reader is typically faster than the standard Multi-AZ standby failover, minimizing write disruption. Option A (promoting a read replica) is not automatic and introduces significant delay. Option C (single-AZ with backups) does not address failover impact. Option D (increasing instance class) does not significantly reduce failover time.

Answer

Create a read replica in a different Availability Zone and promote it during failover.

Answer

Use a single-AZ deployment and rely on automated backups for recovery.

Answer

Increase the DB instance class to reduce failover time.

Question 8

A company uses Amazon DynamoDB with On-Demand capacity for a gaming application. During a new game launch, write traffic spikes 10x normal for 30 minutes. Some write requests receive ProvisionedThroughputExceeded exceptions. What is the MOST likely cause and solution?

Accepted Answer

The partition key is not distributing writes evenly, causing a hot partition. Redesign the partition key for uniform access.. On-Demand capacity can handle spikes but has per-partition throughput limits. If a hot partition exists, writes to that partition may exceed its limit. Option A is correct because uneven partition keys cause throttling. Option B is incorrect because On-Demand does not have table-level limits. Option C is not the primary cause. Option D is incorrect as GSI writes also consume write capacity.

Answer

On-Demand capacity cannot handle sudden spikes. Switch to Provisioned capacity with auto scaling.

Answer

DynamoDB Streams is enabled, causing additional write throttling. Disable streams.

Answer

The table has a global secondary index with a different partition key that is unevenly accessed. Remove the GSI.

Question 9

A database administrator needs to monitor Amazon RDS for PostgreSQL connections and terminate idle connections that have been open for more than 1 hour. Which combination of steps should be taken?

Accepted Answer

Enable audit logging and stream to Amazon CloudWatch Logs. Create a metric filter for connection events. Use CloudWatch Alarm to trigger a Lambda function that runs a SQL query to terminate idle connections.. The correct approach is Option C. Enable audit logging (e.g., using the pgaudit extension) and stream logs to CloudWatch Logs. Create a metric filter to identify connections idle for over 1 hour based on log patterns. Set a CloudWatch Alarm to invoke an AWS Lambda function, which executes a SQL query like pg_terminate_backend(pid) to terminate idle connections. Option A: Performance Insights provides metrics but no automated termination. Option B: RDS event subscriptions do not include idle connection details. Option D: Enhanced Monitoring provides OS-level metrics, not connection idle time.

Answer

Use Amazon RDS Performance Insights to view active connections and manually terminate idle connections via the AWS Management Console.

Answer

Configure an RDS event subscription for 'connection' events and send to Amazon SNS. Use SNS to notify an EC2 instance that runs a script to terminate idle connections.

Answer

Enable RDS Enhanced Monitoring and configure a CloudWatch alarm to invoke an AWS Lambda function that terminates idle connections.

Question 10

A company runs an Amazon Aurora MySQL database with read replicas to handle read traffic. During a recent load test, the primary instance CPU utilization reached 90%, but read replicas remained below 50%. The application uses a custom ORM that connects to a single endpoint. Which change will best distribute read traffic?

Accepted Answer

Configure the application to use the Aurora reader endpoint for read queries.. The Aurora reader endpoint automatically load balances SELECT queries across all read replicas, distributing read traffic effectively. Option B is incorrect: Amazon RDS Proxy provides connection pooling but does not split read/write traffic; it uses the cluster endpoint, which directs to the primary instance. Option C is incorrect: Aurora read replicas are not standard EC2 instances and cannot be placed behind an Application Load Balancer; the reader endpoint is the intended mechanism. Option D is incorrect: The cluster endpoint always points to the primary instance, so using it for reads would not distribute load; Aurora Auto Scaling adds replicas, but they are only utilized when the reader endpoint is used.

Answer

Use Amazon RDS Proxy with read/write splitting.

Answer

Place the read replicas behind an Application Load Balancer.

Answer

Enable Aurora Auto Scaling for replicas and use the cluster endpoint for both read and write.

Question 11

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle using AWS DMS. The source database is 2 TB and has high transaction volume. The migration needs minimal downtime. Currently, full load completes but CDC task fails with 'ORA-1555: snapshot too old' errors. What should the DBA do to resolve this?

Accepted Answer

Increase the undo retention period and undo tablespace size on the source Oracle database.. The 'ORA-1555: snapshot too old' error occurs when Oracle's undo data for a read-consistent view is overwritten before DMS can read it. Increasing the undo retention period and undo tablespace size on the source database ensures that undo data is preserved longer, allowing DMS's CDC task to read consistent data without errors. Option B is correct because it directly addresses the root cause. Option A would restart the full load but not fix the CDC failure. Option C (supplemental logging and larger DMS instance) does not resolve undo retention issues. Option D (reducing transactions) is not practical and may cause data loss. Therefore, the correct solution is to increase undo retention and tablespace size.

Answer

Restart the migration with a new full load and use a smaller task.

Answer

Enable supplemental logging on the source and use a larger DMS instance.

Answer

Reduce the transaction volume by pausing non-essential transactions during CDC.

Question 12

A company uses Amazon DynamoDB with auto scaling enabled. During a flash sale, write traffic spikes and some requests receive ThrottlingException errors. The table's write capacity auto scaling reaches the maximum configured capacity but still throttles. Which TWO actions should resolve the throttling? (Choose TWO.)

Accepted Answer

Increase the maximum write capacity setting for the auto scaling policy.. Increases the maximum write capacity setting, allowing the auto scaling policy to scale higher and handle the increased traffic. Option B addresses hot partitions by reviewing the partition key design to ensure even distribution of writes, which reduces throttling even if capacity is sufficient. Option C (DAX) is a caching layer for reads, not writes, so it does not resolve write throttling. Option D (DynamoDB Streams) captures changes but does not offload write traffic; it's a separate feature for streaming data. Option E (On-Demand mode) would help, but the question asks to resolve throttling with auto scaling enabled; On-Demand is an alternative, not a fix within auto scaling, but it's not the best choice given the context.

Answer

Add a DynamoDB Accelerator (DAX) cluster to cache writes.

Answer

Enable DynamoDB Streams to offload write traffic.

Answer

Disable auto scaling and use On-Demand capacity mode.

Question 13

A company runs an Amazon RDS for SQL Server database. The database size is 500 GB. The company needs to create a test environment with a copy of the production database that refreshes daily. Which THREE steps should be taken to automate this? (Choose THREE.)

Accepted Answer

Use AWS Backup or AWS Lambda to take a manual snapshot of the production DB instance daily.. Creates a manual snapshot of the production DB instance daily using AWS Backup or Lambda. Option D restores that snapshot to a new DB instance in the test environment. Option B updates the test application's connection string to point to the new test instance. Option C is incorrect because a read replica is not a full copy and promoting it would disrupt replication, not provide a daily refreshed copy. Option E is unnecessary because the restored instance can have automated backups enabled, but it is not a required step for the daily refresh process.

Answer

Create a read replica of the production instance and promote it to the test environment.

Answer

Enable automated backups on the test instance after restoration.

Question 14

A company is designing a disaster recovery strategy for an Amazon Aurora MySQL database with a recovery point objective (RPO) of 1 second and a recovery time objective (RTO) of 1 minute. Which TWO solutions meet these requirements? (Choose TWO.)

Accepted Answer

Deploy an Aurora Global Database with a secondary region.. (Aurora Global Database) provides cross-region replication with an RPO of typically less than 1 second and RTO of approximately 1 minute, meeting the requirements. Option E (cross-Region read replicas) can be promoted to a standalone primary in under a minute, and replication lag is sub-second, achieving RPO of 1 second. Option A (Multi-AZ DB cluster) is confined to a single region and does not provide DR across regions. Option B (manual snapshots every hour) results in an RPO of up to 1 hour, far exceeding the 1-second requirement. Option C (automated backups) has a default backup interval of 5 minutes, resulting in an RPO of at least 5 minutes, and point-in-time recovery typically takes longer than 1 minute.

Answer

Use a Multi-AZ DB cluster deployment.

Answer

Take manual snapshots every hour and copy to another region.

Answer

Enable automated backups and perform point-in-time recovery in another region.

Question 15

A financial services company runs a production Amazon Aurora MySQL database cluster (1 writer, 2 readers) in us-east-1. The database stores critical trading data. The company's disaster recovery policy requires an RPO of 5 seconds and an RTO of 1 minute for a regional failure. The current setup does not include any cross-region replication. The database is 5 TB in size. The operations team needs to implement a solution that meets the DR requirements with minimal cost and operational overhead. Which solution should the team implement?

Accepted Answer

Deploy an Aurora Global Database with a secondary cluster in us-west-2. Configure the secondary cluster as a failover target.. Aurora Global Database provides replication across regions with typical RPO of seconds and RTO of minutes. It is the most appropriate solution for low RPO/RTO with minimal overhead. Option B is correct. Option A (automated backups) have an RPO of 5 minutes, which exceeds the required 5 seconds. Option C (DMS) adds cost and complexity. Option D (cross-Region read replicas) can have replication lag exceeding 5 seconds.

Answer

Enable automated backups and configure cross-Region snapshot copy. Use point-in-time recovery in the secondary region.

Answer

Use AWS Database Migration Service (DMS) to continuously replicate changes to an Aurora cluster in us-west-2.

Answer

Create cross-Region read replicas in us-west-2 and set up a replication channel. In disaster, promote a replica.