DBS-C01 Management and Operations Practice Test 2 — 15 Questions

Question 1

A company is migrating an on-premises Microsoft SQL Server database to Amazon RDS for SQL Server. The database uses SQL Server Agent jobs, custom CLR assemblies, and cross-database queries. Which of the following will require modification before migration?

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

Accepted Answer

SQL Server Agent jobs. SQL Server Agent jobs are not supported in Amazon RDS for SQL Server because RDS is a managed service that does not provide access to the underlying operating system or the SQL Server Agent service. To migrate job scheduling, you must use alternatives such as AWS Database Migration Service (DMS) tasks, AWS Lambda, or Amazon RDS for SQL Server native scheduling via stored procedures and Windows Task Scheduler on an EC2 instance.

Answer

Cross-database queries

Answer

Custom CLR assemblies

Answer

Stored procedures that use dynamic SQL

Question 2

A company is using Amazon RDS for MySQL with a cross-Region read replica to support disaster recovery. The primary DB instance is in us-west-2, and the read replica is in us-east-1. The read replica is used for reporting and also serves as a failover target. The operations team notices that the read replica lag is consistently above 10 seconds during peak hours. What should the team do to reduce replica lag?

Accepted Answer

Increase the DB instance class of the read replica.. Increasing the DB instance class of the read replica provides more CPU and memory resources, which allows the replica to apply changes from the binary log more quickly. Cross-Region replication lag is often caused by the replica being unable to keep up with the write rate on the primary, so scaling up the replica directly addresses the bottleneck in applying binlog events.

Answer

Enable Multi-AZ on the primary DB instance.

Answer

Increase the backup retention period for the primary DB instance.

Answer

Disable binary logging (binlog) on the primary DB instance.

Question 3

A company is using an Amazon Aurora MySQL DB cluster. The company wants to implement a backup strategy that supports point-in-time recovery (PITR) with a recovery time objective (RTO) of 15 minutes and a recovery point objective (RPO) of 5 minutes. Which TWO actions should the company take?

Accepted Answer

Configure automated backups with a retention period of at least 1 day.. Aurora automated backups with a retention period of at least 1 day provide continuous backup and point-in-time recovery (PITR) with an RPO of 5 minutes because transaction logs are uploaded every 5 minutes. This meets the required RPO of 5 minutes, and restoring can achieve an RTO under 15 minutes. Option E is correct because Aurora Backtrack allows rewinding the cluster to a specific point in time, achieving an RPO of 5 minutes and an RTO of minutes (typically under 15). No other option meets both the stated RTO and RPO.

Answer

Create manual snapshots every 5 minutes.

Answer

Enable cross-Region replication for the cluster.

Answer

Enable parallel query for the cluster.

Question 4

A company is running a production Amazon DynamoDB table with on-demand capacity. The table experiences occasional throttling during traffic spikes. The table's partition key is a timestamp, and the workload is write-heavy. The operations team needs to reduce throttling. Which THREE actions should the team take? (Choose three.)

Accepted Answer

Add a random suffix to the partition key to distribute writes evenly.. Adding a random suffix to the timestamp partition key breaks the sequential write pattern, distributing writes evenly across all partitions. This prevents hot partitions, which are the root cause of throttling in a write-heavy workload with a monotonically increasing partition key.

Answer

Increase the read capacity units for the table.

Answer

Enable DynamoDB global tables to distribute write traffic.

Question 5

A database administrator runs the above AWS CLI command to troubleshoot replication issues. The DB instance 'mydb' is a read replica of 'my-source-db'. The administrator notices that the replica lag is increasing. Which of the following is the MOST likely cause?

Accepted Answer

The read replica is in a different AWS Region than the source.. When a read replica is in a different AWS Region than the source, the replication traffic must traverse the public internet or a VPN connection, introducing network latency and potential bandwidth constraints. This cross-region lag is a common cause of increasing replica lag, as the asynchronous MySQL replication relies on a single I/O thread to download the binary log events from the source, and any network delay directly impacts the replica's ability to keep up.

Answer

The source DB instance is running a different MySQL version.

Answer

The read replica has Multi-AZ disabled.

Answer

The read replica is using a smaller instance class than the source.

Question 6

An IAM policy is attached to a user who needs to restore an Amazon RDS DB instance from a DB snapshot. The user attempts to restore and receives an 'Access Denied' error. Which missing permission is MOST likely causing the failure?

Accepted Answer

rds:CreateDBInstance. To restore an Amazon RDS DB instance from a DB snapshot, the user must have the `rds:CreateDBInstance` permission. This is because the restore operation internally calls the CreateDBInstance API to create a new DB instance from the specified snapshot. Without this permission, the request fails with an 'Access Denied' error, even if the user has permissions to describe snapshots or instances.

Answer

rds:DescribeDBSnapshots

Answer

rds:DescribeDBInstances

Answer

rds:CreateDBSubnetGroup

Question 7

A company's Amazon RDS for PostgreSQL instance is experiencing high CPU utilization. The DB instance is a db.r5.xlarge with 500 GB of General Purpose SSD (gp2) storage. The application team reports that write-intensive batch jobs are causing latency. The DBA notices that the ReadIOPS metric is low but WriteIOPS is consistently near the instance's maximum. Which action would most effectively reduce write latency?

Accepted Answer

Increase the allocated storage to 1,000 GB to increase baseline IOPS.. Increasing the allocated storage for a gp2 volume from 500 GB to 1,000 GB doubles the baseline IOPS from 1,500 to 3,000 (gp2 baseline is 3 IOPS per GB). Since the write-intensive workload is hitting the maximum IOPS of the current volume, this increase directly raises the IOPS ceiling, reducing write latency without changing storage type.

Answer

Change the storage type to Provisioned IOPS (io1) with the same IOPS.

Answer

Add a read replica to distribute read traffic.

Answer

Enable Multi-AZ deployment to offload writes to a standby instance.

Question 8

A developer accidentally deleted a critical table from an Amazon RDS for MySQL DB instance. Automated backups are enabled with a retention period of 7 days. The deletion occurred 3 hours ago. What is the fastest way to restore the deleted table without affecting other tables?

Accepted Answer

Perform a point-in-time restore of the DB instance to a time just before the deletion, then export the table.. Point-in-time recovery (PITR) allows you to restore the entire DB instance to any second within the automated backup retention period (7 days). By restoring to a time just before the deletion, you can then extract the deleted table using mysqldump or SELECT INTO OUTFILE, and import it back into the original instance. This is the fastest method because it leverages existing automated backups without requiring a manual snapshot or waiting for a full restore of a large instance.

Answer

Use the RDS Query Editor to run a flashback query that retrieves the deleted data.

Answer

Restore the DB instance from the latest manual snapshot and extract the table.

Answer

Restore the table from the automated backup using the AWS Management Console table-level restore feature.

Question 9

A company runs an Amazon Aurora MySQL database cluster with a primary instance and two Aurora Replicas. The application is experiencing occasional deadlocks on the primary instance during peak hours. The deadlocks cause transaction rollbacks that impact customer experience. Which design change should the company implement to minimize deadlocks?

Accepted Answer

Enable Aurora Auto Scaling for read replicas and offload read-only queries to replicas.. Offloading read-only queries to Aurora Replicas reduces the volume of read-write contention on the primary instance. Deadlocks often arise when concurrent transactions compete for the same resources; by directing read traffic to replicas, the primary handles fewer overlapping transactions, lowering the probability of lock conflicts. Aurora Replicas share the same underlying storage volume and serve read traffic without blocking writes on the primary, making this a targeted solution for deadlock reduction.

Answer

Set the transaction isolation level to READ UNCOMMITTED to avoid locks.

Answer

Configure Multi-AZ deployment to automatically failover during deadlocks.

Answer

Increase the DB instance class size to handle more concurrent transactions.

Question 10

A company is using Amazon DynamoDB for a gaming leaderboard. The table has a partition key of 'game_id' and a sort key of 'score'. The application performs a query to retrieve the top 10 scores for a given game_id. The query uses ScanIndexForward: false and Limit: 10. Recently, the query response time has increased. The table's read capacity is 1000 RCU, and the average item size is 1 KB. Which is the most likely cause of the increased latency?

Accepted Answer

A hot partition on the game_id key is causing throttling for that specific partition.. The increased latency is most likely due to a hot partition on the 'game_id' key. When a specific game_id receives a disproportionate amount of write or read traffic, that single partition can exceed its throughput limits (1/1000th of provisioned RCU per partition), causing throttling and retries that degrade query response time. Even though the query uses ScanIndexForward: false and Limit: 10, the request is still constrained by the partition's capacity, and throttling at the partition level leads to increased latency.

Answer

The table lacks a global secondary index on game_id, causing a full table scan.

Answer

The query is using strongly consistent reads instead of eventually consistent reads.

Answer

The provisioned read capacity is too low for the query pattern.

Question 11

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB and has a high number of small transactions. The company needs to minimize downtime during the migration. Which TWO strategies should be used together? (Choose two.)

Accepted Answer

Use AWS Database Migration Service (DMS) to perform a full load and ongoing replication.. AWS DMS with ongoing replication (CDC) is the correct choice because it allows a full load of the 2 TB database followed by continuous replication of changes, minimizing downtime by keeping the target RDS instance nearly synchronized with the source until cutover. This approach is specifically designed for large databases with high transaction volumes, as it reduces the final outage window to seconds or minutes.

Answer

Use Oracle Data Pump to export the database and import into RDS.

Answer

Set up a VPN connection between on-premises and AWS for direct database link.

Answer

Create a manual snapshot of the RDS instance during the migration.

Question 12

A company is using Amazon ElastiCache for Redis to cache frequently accessed data from an RDS MySQL database. The cache hit ratio is currently 85%. The operations team notices that during traffic spikes, the cache eviction rate increases significantly, and the database CPU utilization spikes. The cache cluster uses a single r6g.large node. Which THREE actions should the team take to improve performance? (Choose three.)

Accepted Answer

Add more shards to the cluster to increase total memory.. Adding more shards to the cluster increases the total available memory, which reduces the frequency of evictions during traffic spikes. With more memory, the cache can store more data without forcing out existing entries, thereby maintaining a higher cache hit ratio and reducing the load on the RDS MySQL database.

Answer

Reduce the time-to-live (TTL) for cached items to free up memory faster.

Answer

Configure the cache to use lazy loading only for write-through operations.

Question 13

A company runs a critical e-commerce application on Amazon RDS for PostgreSQL with a db.r5.2xlarge instance and 500 GB of gp2 storage. The application experiences periodic write spikes during flash sales. During these events, the WriteIOPS metric exceeds the provisioned baseline IOPS of 1,500, and the database becomes unresponsive for several seconds. The DBA has configured a CloudWatch alarm on WriteIOPS, but the alarm triggers after the performance issue occurs. The company needs to ensure that the database can handle these spikes without downtime. The budget allows for moderate cost increases. What should the DBA do?

Accepted Answer

Modify the DB instance to use gp3 storage with provisioned IOPS of 5,000.. Gp3 storage provides a baseline of 3,000 IOPS regardless of storage size, and allows provisioning up to 16,000 IOPS independently. By setting provisioned IOPS to 5,000, the database can handle write spikes without exceeding the IOPS limit, preventing unresponsiveness. This solution fits the moderate cost increase budget, as gp3 is typically 20% cheaper than gp2 for equivalent performance.

Answer

Increase the allocated storage to 1,000 GB to increase baseline IOPS to 3,000.

Answer

Enable Performance Insights to identify the problematic queries and tune them.

Answer

Add a read replica and redirect read traffic to it to reduce write contention.

Question 14

A company runs a production Amazon RDS for MySQL Multi-AZ DB instance with 10 TB of storage. The application team notices that database write latency has increased from 5 ms to 80 ms over the past week. The DB instance is a db.r5.8xlarge with 500 GB of gp2 storage. CloudWatch metrics show WriteIOPS averaging 10,000, WriteThroughput at 50 MB/s, and BurstBalance decreasing from 100% to 20% over the same period. The DB instance has no reserved IOPS. The database workload is write-heavy with frequent small transactions. The company needs to resolve the high write latency while minimizing costs and downtime. Which solution should the database specialist recommend?

Accepted Answer

Modify the DB instance to increase the allocated storage to 1 TB using gp2, allowing the volume to operate with higher baseline IOPS and burst credits.. Increasing gp2 storage from 500 GB to 1 TB raises the baseline IOPS from 1,500 (3 IOPS/GB) to 3,000, and also increases the burst credit pool size. With WriteIOPS averaging 10,000, the volume is depleting burst credits faster than they can be replenished, causing BurstBalance to drop to 20% and latency to spike. Doubling the storage provides a higher baseline and more credits, reducing reliance on burst and resolving the latency issue without changing instance class or adding cost for reserved IOPS.

Answer

Create a read replica to offload write traffic to the replica and use it for failover.

Answer

Upgrade the DB instance to a db.r5.16xlarge with more vCPUs and memory to handle higher write throughput.

Answer

Enable Performance Insights to identify slow queries and add database-level caching to reduce write load.

Question 15

A database specialist sees the above error log entries from an Amazon RDS for MySQL DB instance. Which action should be taken to resolve the issue?

Accepted Answer

Restore the DB instance from the latest automated snapshot.. The error log entries indicate corruption in the InnoDB tablespace, likely due to a crash or hardware failure. Restoring from the latest automated snapshot is the correct action because it provides a consistent, point-in-time recovery of the entire database, including all table structures and data, without relying on potentially corrupted files. This approach ensures data integrity and avoids further damage that could occur from attempting repairs on a corrupted instance.

Answer

Increase the allocated storage for the DB instance.

Answer

Reboot the DB instance to clear the error.

Answer

Run the mysqlcheck command to repair the corrupted tables.