DBS-C01 Management and Operations Practice Test 11 — 15 Questions

Question 1

A company is migrating an on-premises Oracle database to Amazon Aurora PostgreSQL. The database has several large tables with frequent INSERT and UPDATE operations. Which TWO actions should be taken to optimize performance after migration?

Accepted Answer

Enable autovacuum and configure it to run more frequently on the large tables.. Options A and D are correct: Autovacuum is essential for managing dead tuples and maintaining performance in PostgreSQL. S3 integration provides fast bulk load/unload. Option B is wrong because synchronous commit reduces performance for transactional workloads. Option C is wrong because Aurora PostgreSQL manages storage automatically; manual partitioning may not be needed. Option E is wrong because RDS Proxy adds overhead for connection pooling but does not directly optimize DML performance.

Answer

Set synchronous_commit to ON to ensure data durability.

Answer

Deploy an RDS Proxy in front of the Aurora cluster to reduce connection overhead.

Answer

Partition the large tables by date to improve query performance.

Question 2

A company uses Amazon DynamoDB for a high-traffic gaming leaderboard. The table has a partition key of 'game_id' and a sort key of 'score'. During a tournament, the application experiences throttling on a single partition. The application uses strongly consistent reads. Which TWO actions should be taken to resolve the throttling and maintain performance?

Accepted Answer

Redesign the partition key to include a random suffix to distribute writes across partitions.. Options B and D are correct: Using a composite key with a shard attribute distributes writes across partitions, while switching to eventually consistent reads for non-critical reads reduces read capacity consumption. Option A is wrong because DAX does not help with write throttling. Option C is wrong because GSI does not distribute the base table's write load. Option E is wrong because increasing RCU does not address the partition hot spot.

Answer

Enable DynamoDB Accelerator (DAX) to cache the most frequently read items.

Answer

Increase the provisioned read capacity units (RCU) for the table.

Answer

Create a global secondary index (GSI) with a different partition key.

Question 3

A company runs an Amazon RDS for MySQL DB instance with Multi-AZ. The application team reports that a recent schema change caused a significant increase in replication lag. The instance has a read replica in a different AWS Region. Which THREE actions should be taken to reduce replication lag?

Accepted Answer

Identify and optimize any long-running transactions or DDL statements that may be blocking replication.. Options A, C, and E are correct: Identifying and optimizing long-running transactions and DDL statements reduces lag. Monitoring replication metrics helps pinpoint the cause. Using a lower isolation level reduces locking. Option B is wrong because disabling binary logging stops replication entirely. Option D is wrong because increasing instance class may help but is not a targeted fix; the other options address common causes of lag.

Answer

Increase the DB instance class for both the primary and read replica to improve performance.

Answer

Disable binary logging on the primary instance to reduce I/O overhead.

Question 4

Refer to the exhibit. An IAM policy is attached to a role used by an application running on Amazon EC2. The application needs to read items from a DynamoDB table named 'MyTable' and create manual snapshots of an RDS instance. What is the issue with the policy?

Accepted Answer

The policy does not grant any DynamoDB read actions (e.g., GetItem, Query, Scan) required for the application.. Option B is correct because the policy grants only 'PutItem' and 'DeleteItem' actions on the DynamoDB table, but the application needs to read items (e.g., 'GetItem' or 'Scan'). Additionally, 'CreateDBSnapshot' requires specifying the DB instance ARN, not just '*', but the primary issue is the missing read permissions. Option A is wrong because 'DescribeDBInstances' with '*' is allowed but not the main issue. Option C is wrong because the policy is structured correctly. Option D is wrong because 'CreateDBSnapshot' is allowed on '*', but the missing read action is the critical flaw.

Answer

The policy allows 'DescribeDBInstances' on all resources, which is too permissive.

Answer

The policy uses 'Resource': '*' for DynamoDB, which should be the table ARN.

Answer

The policy grants 'CreateDBSnapshot' on all resources, which is insufficient; it should be scoped to the specific DB instance.

Question 5

Refer to the exhibit. An IAM policy statement allows creating manual snapshots for an RDS instance. A database administrator is unable to create a snapshot from the AWS Management Console. The error message indicates insufficient permissions. What is the likely cause?

Accepted Answer

The policy does not include necessary read actions (e.g., 'DescribeDBInstances', 'DescribeDBSnapshots') that the console uses.. Option D is correct because the console may try to list snapshots or describe instances, which require additional actions like 'DescribeDBSnapshots' and 'DescribeDBInstances'. The condition restricts the region, but the missing actions cause the failure. Option A is wrong because the region condition is correctly written. Option B is wrong because the resource ARN is correct. Option C is wrong because the condition uses 'StringEquals' correctly.

Answer

The condition key 'aws:RequestedRegion' is misspelled.

Answer

The resource ARN is incorrect; it should include the snapshot ARN.

Answer

The condition uses 'StringEquals' but should use 'StringLike' for region matching.

Question 6

Refer to the exhibit. A database administrator runs the AWS CLI command shown. The output is: ["available", false]. What does this output indicate about the DB instance?

Accepted Answer

The DB instance is available and is not configured for Multi-AZ.. Option B is correct because the output shows the DBInstanceStatus is 'available' and MultiAZ is false. Option A is wrong because MultiAZ is false. Option C is wrong because MultiAZ false means it is not configured for Multi-AZ. Option D is wrong because the status is 'available', not 'stopped'.

Answer

The DB instance is in the process of being modified to enable Multi-AZ.

Answer

The DB instance is in a Multi-AZ deployment and is available.

Answer

The DB instance is stopped and is not in a Multi-AZ configuration.

Question 7

A company runs a critical application on Amazon RDS for PostgreSQL with Multi-AZ. The database has a large table (over 500 GB) that is frequently updated. The operations team notices that the primary instance's CPU usage is consistently above 90%, and the replica lag between the primary and standby is increasing during peak hours. The application can tolerate a few seconds of downtime. The team needs to reduce CPU load and improve write performance without changing the application code. Which action should be taken?

Accepted Answer

Upgrade the DB instance class to a larger size with more vCPUs.. Option A is correct because upgrading to a larger instance class provides more CPU capacity, reducing the load and replication lag. Option B is wrong because read replicas are for read scaling, not for reducing write load on the primary. Option C is wrong because reducing replication lag is not achieved by changing backup retention. Option D is wrong because switching to asynchronous replication is not possible in Multi-AZ and would compromise durability.

Answer

Increase the backup retention period to reduce I/O during backups.

Answer

Modify the DB instance to use asynchronous replication instead of synchronous.

Answer

Create a read replica in the same region and offload read queries to it.

Question 8

A company uses Amazon DynamoDB to store IoT sensor data. Each sensor writes a record every second. The table has a partition key of 'sensor_id' and a sort key of 'timestamp'. Over time, the team notices that write performance degrades for certain sensors that generate more data. The table uses provisioned capacity with auto scaling enabled. The application uses eventual consistency. The team needs to ensure consistent write performance without throttling. Which action should be taken?

Accepted Answer

Modify the partition key to include a random number or prefix to distribute writes evenly.. Option C is correct because adding a random suffix to the partition key distributes writes across partitions, avoiding hot partitions. Option A is wrong because increasing WCU does not solve the partition hot spot, as the limit per partition is fixed. Option B is wrong because switching to on-demand still has per-partition limits. Option D is wrong because a GSI does not change the base table's write distribution.

Answer

Increase the provisioned write capacity units (WCU) to a higher value.

Answer

Switch the table to on-demand capacity mode.

Answer

Create a global secondary index (GSI) with a different partition key to handle writes.

Question 9

A company has an Amazon Redshift cluster with two dc2.large nodes. The cluster is used for daily ETL jobs and reporting. The operations team receives an alert that the cluster's disk space is 90% full. The ETL jobs are failing with 'disk full' errors. The team needs to resolve the issue quickly with minimal downtime. Which action should be taken?

Accepted Answer

Resize the cluster to a larger node type, such as dc2.large to ds2.xlarge, or add more nodes.. Option A is correct because resizing to a larger node type or adding nodes increases storage capacity. Option B is wrong because VACUUM only reclaims space from deleted rows; it may not free enough space. Option C is wrong because deep copy is a workaround to reorganize data but does not increase capacity. Option D is wrong because unloading data to S3 does not free space on the cluster.

Answer

Perform a deep copy to re-sort and reclaim space.

Answer

Run the VACUUM command to reclaim space from deleted rows.

Answer

Unload old data to Amazon S3 and delete from the cluster.

Question 10

A company runs a production Amazon RDS for MySQL DB instance with Multi-AZ. The database is used by a web application. The application team reports that the database is experiencing intermittent connection timeouts and increased latency. The CloudWatch metrics show that the database connections spike to the maximum allowed (max_connections) during peak hours, and the CPU utilization is high. The team needs to resolve the connection issues without modifying the application code. The application uses connection pooling at the application layer. Which action should be taken?

Accepted Answer

Deploy an Amazon RDS Proxy in front of the DB instance.. Option B is correct because RDS Proxy manages connection pooling efficiently, reducing the number of connections to the database and lowering CPU overhead. Option A is wrong because increasing max_connections may lead to resource exhaustion. Option C is wrong because read replicas do not reduce write connection load. Option D is wrong because switching to a smaller instance would worsen the problem.

Answer

Create a read replica and direct read queries to it.

Answer

Increase the 'max_connections' parameter to allow more connections.

Answer

Change the DB instance class to a smaller size to reduce the maximum connections.

Question 11

A company is migrating its on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size and the network bandwidth is 100 Mbps. The migration must have minimal downtime. Which TWO approaches should be used together to achieve this?

Accepted Answer

Use AWS Database Migration Service (DMS) with ongoing replication to keep the target in sync.. AWS DMS with ongoing replication allows continuous data replication with minimal downtime. AWS Snowball can be used for the initial large data transfer to avoid prolonged network transfer. Option B (increasing bandwidth) is not feasible quickly; Option C (taking a backup and restoring) would cause downtime; Option E (SCT) is for schema conversion, not data migration.

Answer

Take a full backup of the source database and restore it to Amazon RDS.

Answer

Increase the network bandwidth to 1 Gbps to speed up the transfer.

Answer

Use AWS Schema Conversion Tool (SCT) to convert the schema before migration.

Question 12

An e-commerce application uses Amazon Aurora MySQL with a Multi-AZ DB cluster. During a recent load test, the application experienced increased read latency. The database cluster consists of one writer and two reader instances. Which THREE actions should be taken to improve read performance?

Accepted Answer

Configure cross-Region read replicas.. Adding more reader instances distributes the read load. Using Aurora Auto Scaling automatically adjusts reader capacity. Enabling read replicas in different regions can offload read traffic locally. Option B (increasing writer instance size) does not directly help reads; Option D (using ElastiCache) is for application-level caching, not database read scaling; Option E (using DynamoDB Accelerator) is irrelevant.

Answer

Increase the instance class of the writer instance.

Answer

Implement Amazon ElastiCache for caching frequent queries.

Question 13

Refer to the exhibit. An IAM policy is attached to a user who needs to manage Amazon RDS DB instances. When the user attempts to modify a DB instance, they receive an 'AccessDenied' error. What is the most likely cause?

Accepted Answer

The policy is missing the 'rds:ListTagsForResource' permission needed for the console.. The policy uses 'ModifyDBInstance' but the correct action is 'ModifyDBInstance' (note: actual action is 'rds:ModifyDBInstance' — but the error could be due to missing 'rds:ModifyDBInstance' for a specific resource if the policy has conditions, but here resource is '*'. However, a common mistake is using 'ModifyDBInstance' instead of 'ModifyDBInstance'? Actually both are correct. The issue might be that the policy does not allow 'rds:ListTagsForResource' which is required for console access. But the question says they receive AccessDenied when modifying. The most plausible answer is that the user is trying to modify a DB instance that has 'DeletionProtection' enabled and the policy does not explicitly allow that action? No. Actually, the error is likely due to the policy missing the 'rds:ModifyDBInstance' action? But it's there. Wait, the exhibit shows 'ModifyDBInstance' which is correct. Hmm. Let me think: The policy allows 'ModifyDBInstance' on all resources, but the user might be using the AWS Management Console which requires additional permissions like 'rds:DescribeDBInstances' (which is present) and 'rds:ListTagsForResource' (not present). So the most likely cause is missing permissions for console-specific actions. Option D mentions 'ListTagsForResource' which is needed for console. So D is correct.

Answer

The policy does not include the 'rds:ModifyDBInstance' action for the specific DB instance ARN.

Answer

The user is trying to modify a Multi-AZ DB instance which requires additional permissions.

Answer

The policy requires a condition to allow modifications during the maintenance window.

Question 14

A company has an Amazon RDS for PostgreSQL DB instance with automated backups enabled. The retention period is set to 7 days. A developer accidentally performed a DROP TABLE operation on a critical table 2 days ago. How can the table be recovered with minimal data loss?

Accepted Answer

Perform a point-in-time restore to a time just before the DROP TABLE operation.. Point-in-time restore allows recovery to any time within the backup retention period. The table was dropped 2 days ago, so restoring to a time just before the drop will recover the data. Option A (restore from oldest snapshot) would lose data from the last 7 days; Option C (manual backup) is not available; Option D (replicate to another region) does not help.

Answer

Use the pg_dump utility to create a manual backup and restore it.

Answer

Create a read replica of the DB instance and promote it to a standalone instance.

Answer

Restore the DB instance from the oldest automated snapshot.

Question 15

A company runs a critical application on Amazon RDS for MySQL with Multi-AZ deployment. The application performs frequent writes. The DB instance's CPU utilization is consistently above 80%, and the write latency is high. The company wants to improve write performance without changing the application code. Which solution is MOST effective?

Accepted Answer

Migrate the database to Amazon Aurora MySQL.. Migrating to Amazon Aurora MySQL provides better write performance due to its distributed storage and optimized write path. Option A (increasing instance size) can help but may not be as effective as Aurora; Option C (adding read replicas) does not help write performance; Option D (using Multi-AZ with synchronous replication) already has Multi-AZ, and the latency is due to CPU, not replication.

Answer

Enable Multi-AZ with synchronous replication to a standby instance.

Answer

Add a read replica to offload read traffic.

Answer

Increase the DB instance class to a larger size with more vCPUs.