DBS-C01 Management and Operations Practice Test 13 — 15 Questions

Question 1

A company is experiencing increased latency on their Amazon RDS for PostgreSQL instance. The application team reports that queries are taking longer than usual. The database metrics show high CPU utilization and a spike in write operations. Which initial step should the database specialist take to diagnose the issue?

Accepted Answer

Enable Performance Insights on the DB instance to analyze the workload.. Enabling Performance Insights provides a detailed performance analysis and helps identify the root cause of the latency. It is the recommended first step for diagnosing database performance issues.

Answer

Create a read replica to offload read traffic from the primary instance.

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Modify the DB instance to a larger instance class to handle the load.

Answer

Enable enhanced monitoring to get OS-level metrics of the DB instance.

Question 2

A database administrator needs to automate the backup process for an Amazon RDS for MySQL DB instance. The backups must be retained for 30 days and should be taken daily. Which AWS service should be used to implement this automation?

Accepted Answer

Amazon RDS automated backups. Amazon RDS automated backups are the native, built-in mechanism for backing up RDS DB instances. They automatically take daily snapshots during the backup window and retain transaction logs for point-in-time recovery. By default, the retention period can be set from 1 to 35 days, so configuring it to 30 days meets the requirement without any additional services or custom scripting.

Answer

Amazon S3 lifecycle policies

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AWS Backup

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AWS Lambda with custom scripts

Question 3

A company is running an Amazon DynamoDB table with on-demand capacity mode. The table experiences occasional throttling during peak hours. The application team wants to understand the read/write patterns to optimize the table design. Which approach should the database specialist take to analyze the throttling events?

Accepted Answer

Enable CloudWatch Contributor Insights for DynamoDB to identify throttled requests.. CloudWatch Contributor Insights analyzes high-cardinality attributes and provides detailed information about throttling requests, such as which items or partitions are causing throttling.

Answer

Enable DynamoDB Accelerator (DAX) to cache reads and reduce throttling.

Answer

Use AWS CloudTrail to log all DynamoDB API calls and analyze the logs.

Answer

Switch to provisioned capacity mode with auto scaling to handle the spikes.

Question 4

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database size is 500 GB. The migration must have minimal downtime. Which AWS service should be used to perform the migration?

Accepted Answer

AWS Database Migration Service (DMS). AWS Database Migration Service (DMS) is the correct choice because it supports heterogeneous migrations from Oracle to Amazon RDS for Oracle with minimal downtime. DMS can perform continuous replication using Oracle's change data capture (CDC) via LogMiner or binary reader, allowing the source database to remain operational during the migration. This makes it ideal for a 500 GB database where downtime must be minimized.

Answer

AWS Snowball Edge

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AWS DataSync

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Amazon RDS for Oracle snapshot copy

Question 5

A database administrator needs to monitor the number of connections to an Amazon RDS for MySQL DB instance. Which Amazon CloudWatch metric should be used?

Accepted Answer

DatabaseConnections. The DatabaseConnections metric in CloudWatch shows the number of current connections to the DB instance.

Answer

NetworkThroughput

Answer

ConnectionAttempts

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ActiveTransactions

Question 6

A company uses Amazon Aurora MySQL-Compatible Edition. The database specialist notices that the DB cluster's failover time is longer than expected. The primary instance is using a db.r5.large instance class. Which change would most likely reduce the failover time?

Accepted Answer

Use a larger instance class for the Aurora Replicas.. Using a larger instance class for Aurora replicas ensures they can handle the workload after failover, potentially reducing failover time. However, the key factor is that Aurora failover is typically fast, but if replicas are undersized, the time to promote and become fully operational increases. Using a larger instance class for the replicas (or all instances) can help.

Answer

Enable Backtrack on the DB cluster.

Answer

Increase the number of Aurora Replicas.

Answer

Enable Multi-AZ deployment for the DB cluster.

Question 7

A company is using Amazon Redshift for data warehousing. The database administrator needs to identify which queries are consuming the most resources. Which system view should be queried?

Accepted Answer

STV_RECENTS. The STV_RECENTS system view in Amazon Redshift provides a list of currently running and recently completed queries, including their process IDs, user names, and execution status. This makes it the correct choice for identifying which queries are consuming the most resources at the moment, as it directly reflects active and recent workload.

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SVV_TABLES

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STL_LOAD_ERRORS

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STL_DDLTEXT

Question 8

A company needs to ensure that all changes to an Amazon RDS DB instance are logged for auditing purposes. Which AWS service should be enabled?

Accepted Answer

AWS CloudTrail. AWS CloudTrail is the correct service because it records API activity for Amazon RDS, including calls to create, modify, or delete DB instances, as well as changes to security groups, parameter groups, and automated backups. CloudTrail logs these events to an S3 bucket or CloudWatch Logs, providing a durable audit trail for all management-plane operations on the RDS DB instance. This directly meets the requirement to log all changes for auditing purposes.

Answer

AWS Config

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Amazon GuardDuty

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Amazon Inspector

Question 9

A database administrator sees the above error logs in CloudWatch for an Amazon RDS for PostgreSQL DB instance. The application team confirms that the password for 'app_user' is correct. What is the most likely cause of the authentication failures?

Accepted Answer

The host '10.0.1.50' is not listed in the pg_hba.conf file.. The errors show authentication failures from a specific host. If the password is correct, the most likely cause is that the host is not allowed by the pg_hba.conf configuration. RDS for PostgreSQL uses DB parameter groups to control pg_hba.conf rules; the rds.force_ssl parameter or the pg_hba.conf entries may not include that host.

Answer

The password has expired for 'app_user'.

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The user 'app_user' does not have the LOGIN privilege.

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The database is in read-only mode.

Question 10

Which TWO of the following are valid strategies for reducing costs for an Amazon DynamoDB table with on-demand capacity mode? (Choose TWO.)

Accepted Answer

Implement DynamoDB Accelerator (DAX) to cache reads.. Implementing DAX reduces the number of read requests to the underlying DynamoDB table by serving cached results, which lowers read capacity consumption and thus reduces costs for on-demand tables. Switching to provisioned capacity with auto scaling allows you to pay for a baseline of read/write capacity units rather than per-request pricing, which is more cost-effective for predictable or steady workloads.

Answer

Use Amazon DynamoDB TTL to automatically delete expired data.

Answer

Enable DynamoDB global tables to distribute traffic.

Answer

Use DynamoDB Streams to process updates asynchronously.

Question 11

Which THREE of the following are required to set up cross-Region replication for an Amazon RDS for MySQL DB instance? (Choose THREE.)

Accepted Answer

The backup retention period on the source must be at least 1 day.. Option A is correct because Amazon RDS requires a minimum backup retention period of 1 day on the source DB instance to enable automated backups, which are necessary for cross-Region replication. The backup retention period determines how long automated backups are retained, and a value of at least 1 day ensures that the source instance can generate the binary logs needed for replication to a read replica in another Region.

Answer

The source DB instance must be in a VPC.

Answer

The source DB instance must be a Multi-AZ deployment.

Question 12

Which TWO of the following are benefits of using Amazon RDS Proxy? (Choose TWO.)

Accepted Answer

Reduces the number of database connections by pooling them.. Amazon RDS Proxy acts as a connection broker between your application and the database, maintaining a pool of established connections. When the application opens a new connection, RDS Proxy reuses an idle connection from the pool, which reduces the total number of database connections and prevents the database from being overwhelmed. This pooling mechanism directly addresses the issue of connection exhaustion, especially in serverless or highly concurrent environments.

Answer

Automatically encrypts all traffic between the application and the database.

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Provides built-in read/write splitting for read replicas.

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Reduces storage costs by compressing data in transit.

Question 13

A database administrator is creating an IAM policy to allow a DevOps engineer to manage production RDS instances. The policy above is attached to the engineer's IAM role. The engineer reports that they cannot create a new DB instance with the identifier 'prod-analytics'. What is the most likely reason?

Accepted Answer

The engineer does not have permissions to pass an IAM role to the DB instance if one is specified.. The policy grants permissions to resources matching 'prod-*', but creating a DB instance requires the 'rds:CreateDBInstance' action on the 'arn:aws:rds:us-east-1:123456789012:db:prod-*' resource. However, the CreateDBInstance API call also requires permissions on other resources such as security groups, subnets, etc. But the error is likely because the policy does not allow the action on the specific resource, but the resource ARN matches. Actually, the most common issue is that the policy does not include 'rds:CreateDBInstance' on the 'aws:RequestTag' condition or the resource ARN pattern is incorrect. However, the policy looks correct for the resource. A common mistake is that the policy does not allow 'rds:CreateDBInstance' on the 'arn:aws:rds:us-east-1:123456789012:db:*' for creation, but the policy uses 'prod-*'. That should work. Another possibility is that the engineer is trying to create the instance in a different region or account. But the exhibit shows the policy is for 'us-east-1'. So the most likely reason is that the 'rds:CreateDBInstance' action requires additional permissions on other resources (like EC2 security groups) that are not granted.

Answer

The policy does not allow the 'rds:CreateDBInstance' action on the required resource because the resource ARN pattern is incorrect.

Answer

The policy does not include the 'rds:CreateDBSecurityGroup' action.

Answer

The policy does not include the 'rds:CreateDBInstance' action for all regions.

Question 14

A database administrator runs the 'describe-db-clusters' CLI command and sees the above output. The earliest restorable time is December 1, 2023. However, the backup retention period is 7 days. Why is the earliest restorable time earlier than 7 days from now (assuming today is December 5, 2023)?

Accepted Answer

Automated backups are only kept for 7 days, but manual snapshots extend the recovery window.. The earliest restorable time is the earliest point to which you can restore. With a backup retention period of 7 days, the earliest point should be 7 days before the latest restorable time. In this case, the latest restorable time is December 5, so the earliest should be November 28. But it shows December 1, which is only 4 days before. This is because manual snapshots or other factors can extend the restorable range. Actually, the earliest restorable time is determined by the oldest backup (automated or manual) plus transaction logs. If manual snapshots are taken, they can extend the range. The most likely reason is that there are manual snapshots taken before the automated backup window.

Answer

The backup retention period is misconfigured; it should be 30 days.

Answer

The cluster was created on December 1, so that is the earliest point available.

Answer

The 'earliestRestorableTime' is calculated based on the latest transaction log, not backup retention.

Question 15

A database administrator sees repeated 'Aborted connection' warnings in the RDS for MySQL error log. The application team reports intermittent connection errors. What is the most likely cause of these aborted connections?

Accepted Answer

The application is closing the database connection abruptly without completing the handshake.. The error 'Got an error reading communication packets' typically indicates a network issue or the client disconnecting unexpectedly. The most common cause is that the database connection is being closed by the application without properly closing the connection, or the network between the application and database is unstable. Option C is plausible but less likely because the error message points to communication issues.

Answer

The wait_timeout parameter is too low, causing idle connections to be terminated.

Answer

The user 'appuser' does not have permission to connect from host '10.0.0.50'.

Answer

The database instance is running out of memory, causing connection drops.