DBS-C01 Practice Test 50 — 15 Questions

Question 1

A database specialist created the above IAM policy for a user. When the user attempts to delete an item from the Orders table, what happens?

Accepted Answer

The user cannot delete items because the Deny statement takes precedence.. Option C is correct. The explicit Deny overrides the Allow, so the user cannot delete items. Option A is wrong because Deny takes precedence. Option B is wrong because the Deny explicitly restricts deletion. Option D is wrong because the policy explicitly denies deletion.

Answer

The user cannot delete items because the policy does not include a condition.

Answer

The user can delete items because the Allow statement grants permission.

Answer

The user can delete items only if they have another policy that allows it.

Question 2

A company is running a MongoDB-compatible Amazon DocumentDB cluster. The application is experiencing high write latency during peak hours. The cluster has one writer and two readers. The DBA suspects that the issue is due to a large number of indexes on the collection. What should the DBA do to verify this hypothesis without affecting production?

Accepted Answer

Create a clone of the cluster using the 'Clone Cluster' feature and test index changes on the clone.. Option D is correct because creating a clone of the cluster in the same account allows testing in an isolated environment without impacting production. Option A is incorrect because using the profiler to identify slow queries does not directly test the impact of indexes. Option B is incorrect because AWS DMS is used for migration, not for testing index impact. Option C is incorrect because restoring a snapshot into a new cluster is disruptive as it requires taking a snapshot and restoring, which can be time-consuming and does not provide real-time data.

Answer

Take a snapshot of the cluster and restore it to a new cluster to test index changes.

Answer

Use AWS DMS to replicate data to a test cluster and perform index testing there.

Answer

Enable the profiler on the production cluster to capture slow queries and analyze the index usage.

Question 3

A company uses Amazon DynamoDB with on-demand capacity mode for a critical application. During a marketing campaign, the application experienced throttled requests despite the on-demand mode. The table has a single partition key. The database specialist notices that the throttling occurs sporadically even though overall traffic is within limits. What is the most likely cause?

Accepted Answer

The table's partition key is causing a hot partition, leading to throttling on that partition.. On-demand mode accommodates traffic spikes, but if a single partition key is used, all traffic goes to one partition. DynamoDB partitions data by partition key; a single hot key can throttle requests even if overall throughput is within limits. Provisioned capacity is not used. Auto scaling is not relevant. The partition limit is a hard limit.

Answer

The table's provisioned capacity is set too low.

Answer

The table's auto scaling is not configured correctly.

Answer

The application is exceeding the DynamoDB account-level throughput limits.

Question 4

A company is migrating an on-premises Oracle database to Amazon Aurora PostgreSQL. The database has several stored procedures that use Oracle-specific PL/SQL. The team needs to minimize manual code changes. Which AWS service or tool should be used to automate the conversion of the stored procedures?

Accepted Answer

AWS Schema Conversion Tool (AWS SCT). Option B is correct because the AWS Schema Conversion Tool (AWS SCT) is designed to convert database schemas, including stored procedures, from one engine to another. Option A is wrong because DMS is for data migration, not schema or code conversion. Option C is wrong because SCT can handle the conversion, and a manual rewrite is not necessary; SCT automates most of it. Option D is wrong because the PostgreSQL compatibility mode in Amazon Aurora does not automatically convert Oracle PL/SQL.

Answer

Amazon Aurora PostgreSQL native compatibility

Answer

AWS Database Migration Service (AWS DMS)

Answer

Manual rewrite using PostgreSQL PL/pgSQL

Question 5

The exhibit shows the output of a MySQL command run on an Amazon RDS for MySQL DB instance. The database is experiencing frequent checkpointing that is causing I/O spikes. The parameter innodb_log_file_size is currently 256 MB. Which change should be made to reduce checkpoint frequency?

Accepted Answer

Increase the value of innodb_log_file_size to 1 GB.. Option A is correct because increasing the size of the InnoDB redo log files reduces checkpoint frequency. Option B is wrong because decreasing would increase checkpoint frequency. Option C is wrong because innodb_flush_log_at_trx_commit controls durability, not checkpoint frequency. Option D is wrong because innodb_buffer_pool_size affects memory, not directly checkpointing.

Answer

Decrease the value of innodb_log_file_size to 128 MB.

Answer

Set innodb_flush_log_at_trx_commit to 0.

Answer

Increase the value of innodb_buffer_pool_size.

Question 6

A company uses Amazon RDS for MySQL with read replicas. The application writes to the primary and reads from the replicas. Occasionally, the application reads stale data from the replicas. Which action would ensure read-after-write consistency without impacting write performance?

Accepted Answer

Configure the application to read from the primary instance for critical queries.. Using the primary instance for reads that require consistency ensures the application reads the latest data. Session-level replication checks are not supported in standard MySQL.

Answer

Set the replica_read_consistency parameter to 'session'.

Answer

Use the reader endpoint and increase the replica lag threshold.

Answer

Enable the 'rds_set_replication_status' parameter on the read replicas.

Question 7

A company needs to audit all SQL queries executed on an Amazon RDS for SQL Server database. Which AWS service should be used?

Accepted Answer

Amazon RDS Database Activity Streams. Option C is correct because database activity streams provide a near real-time feed of database activity for auditing. Option A is wrong because CloudTrail logs API calls, not SQL queries. Option B is wrong because CloudWatch Logs can store logs but needs a source; RDS does not natively send SQL logs to CloudWatch. Option D is wrong because VPC Flow Logs capture network traffic, not SQL queries.

Answer

Amazon VPC Flow Logs

Answer

Amazon CloudWatch Logs

Answer

AWS CloudTrail

Question 8

A developer needs to restore an Amazon RDS for PostgreSQL DB instance to a specific point in time within the retention period. What must be enabled for this operation to be possible?

Accepted Answer

Automated backups with a retention period greater than 0.. Option A is correct because automated backups (enabled by default with a retention period) are required for point-in-time recovery (PITR). Option B is incorrect because Multi-AZ is not required for PITR. Option C is incorrect because read replicas are not needed. Option D is incorrect because deletion protection prevents accidental deletion but does not affect PITR.

Answer

Deletion protection enabled.

Answer

A read replica in the same region.

Answer

Multi-AZ deployment.

Question 9

A company has an Amazon RDS for MySQL DB instance that is running low on storage. The current allocated storage is 500 GB, and the free space is down to 10 GB. The database administrator wants to increase storage with minimal downtime. Which action should be taken?

Accepted Answer

Use the AWS Management Console to modify the DB instance and increase the allocated storage.. RDS supports modifying storage online with minimal downtime. Increasing allocated storage from 500 GB to, for example, 600 GB can be done via a modification to the DB instance. The instance remains available during the modification, though a brief performance impact may occur. Stopping the instance is unnecessary. Creating a snapshot and restoring would cause longer downtime. Waiting for autoscaling might not be quick enough if space is critically low.

Answer

Stop the DB instance, modify the allocated storage, and start the instance.

Answer

Create a snapshot of the current DB instance, restore it to a new larger instance, and point the application to the new endpoint.

Answer

Enable storage autoscaling and wait for the automatic increase.

Question 10

A database administrator is troubleshooting a slow-running query on an Amazon RDS for PostgreSQL DB instance. The query plan shows a sequential scan on a large table. The table has a primary key and an index on the column used in the WHERE clause. Why might the query optimizer choose a sequential scan over an index scan?

Accepted Answer

The query is expected to return a large percentage of rows.. Option B is correct because if the optimizer estimates that a large percentage of rows will be returned, a sequential scan can be more efficient than random I/O from an index. Option A is wrong because outdated statistics can cause suboptimal plans, but the question asks for a reason the planner might choose sequential scan; outdated stats could lead to either choice. Option C is wrong because the presence of an index does not force its use; the optimizer decides. Option D is wrong because the query has a WHERE clause, so a full table scan is not the only option, but it may be chosen due to the selectivity.

Answer

The query is a SELECT * without a WHERE clause.

Answer

The table's statistics are outdated.

Answer

The index on the column is not being used because it is a composite index with a different column order.

Question 11

The exhibit shows an IAM policy attached to a user. The user needs to create a manual snapshot of an RDS DB instance named 'production-db'. Which action will the user be able to perform?

Accepted Answer

Create a manual snapshot of 'production-db' with the name 'mydb-production-snapshot'.. Option C is correct because the policy allows CreateDBSnapshot on resources matching 'mydb-*', but the snapshot name must match that pattern. Option A is wrong because DeleteDBInstance is denied. Option B is wrong because the user can create snapshots matching the pattern. Option D is wrong because the user can describe instances.

Answer

Create a manual snapshot of 'production-db' with the name 'production-db-snapshot'.

Answer

Describe the 'production-db' DB instance.

Answer

Delete the 'production-db' DB instance.

Question 12

A company is using Amazon DynamoDB with on-demand capacity for a serverless web application. The application experiences occasional throttling. The DynamoDB table has a simple primary key (partition key only). The throttled requests are related to a small number of partition keys. What is the MOST likely cause?

Accepted Answer

The partition key design leads to uneven access patterns, causing a hot partition.. Option B is correct because throttling on a few partition keys indicates a hot partition. Option A is wrong because on-demand capacity handles overall traffic, but partition-level limits still apply. Option C is wrong because a simple primary key is fine, but the data distribution is the issue. Option D is wrong because on-demand capacity automatically scales, but not per partition beyond the limit.

Answer

On-demand capacity has a per-partition throughput limit that is too low.

Answer

The table uses a composite primary key, which limits throughput.

Answer

The table's read/write capacity mode is set to provisioned instead of on-demand.

Question 13

A company runs an Amazon DynamoDB table with on-demand capacity. They notice that a specific partition key receives a high volume of read requests, causing throttling for that partition. What is the BEST solution to distribute the load evenly?

Accepted Answer

Add a random suffix to the partition key values to increase partition cardinality.. Adding a suffix to the partition key to create multiple partitions distributes read load across partitions.

Answer

Create a global secondary index with a different partition key.

Answer

Use DynamoDB Accelerator (DAX) to cache reads.

Answer

Switch the table to provisioned capacity with auto-scaling.

Question 14

A company runs a critical Amazon RDS for PostgreSQL database. They notice that the 'DiskQueueDepth' metric is consistently high and the 'FreeStorageSpace' is below 10%. The database is used for OLTP workloads. What is the MOST immediate action to take?

Accepted Answer

Modify the DB instance to increase allocated storage.. Option B is correct because increasing storage quickly avoids potential downtime and I/O throttling. Option A is wrong because switching to Provisioned IOPS addresses latency but not the storage shortage. Option C is wrong because adding a read replica does not increase storage on the primary. Option D is wrong because modifying the instance class may not address storage space.

Answer

Upgrade to a larger DB instance class.

Answer

Switch the instance to Provisioned IOPS storage.

Answer

Create a read replica to offload read traffic.

Question 15

A company is using Amazon DynamoDB with on-demand capacity. The operations team wants to monitor for throttled requests. Which TWO metrics from Amazon CloudWatch should be used to set up an alarm for throttling? (Select TWO.)

Accepted Answer

ThrottledPutRecords. Options A and B are correct. 'ThrottledGetRecords' and 'ThrottledPutRecords' are CloudWatch metrics that directly indicate throttled read and write requests. Option C is incorrect because 'ReadThrottleEvents' is not a standard DynamoDB metric. Option D is incorrect because 'ProvisionedReadCapacityUnits' is for provisioned mode. Option E is incorrect because 'ConsumedWriteCapacityUnits' shows consumed capacity, not throttling.

Answer

ConsumedWriteCapacityUnits

Answer

ReadThrottleEvents

Answer

ProvisionedReadCapacityUnits

DBS-C01 Practice Test 50 — 15 Questions

Exhibit

DBS-C01 Practice Test 50 — 15 Questions

Exhibit