DBS-C01 Management and Operations Practice Test 16 — 15 Questions

Question 1

A database administrator is troubleshooting a sudden increase in read latency on an Amazon RDS for PostgreSQL instance. The instance has 200 GB of General Purpose SSD (gp2) storage with 600 provisioned IOPS. The administrator notices that the average queue depth is consistently above 4. Which action is the MOST effective way to reduce read latency?

Accepted Answer

Migrate to an io1 volume with 3000 provisioned IOPS.. Option A increases IOPS by scaling up to an io1 volume, which directly addresses the queue depth issue and improves latency. Option B is incorrect because increasing instance size may not resolve IOPS bottleneck. Option C is incorrect because Multi-AZ does not improve read performance for a single instance. Option D is incorrect because increasing storage alone does not guarantee more IOPS for gp2.

Answer

Enable Multi-AZ deployment to offload reads to the standby.

Answer

Change the instance type to a larger size with more vCPUs.

Answer

Increase the allocated storage to 500 GB without changing IOPS.

Question 2

A company runs an Amazon Aurora MySQL database cluster with one writer and one reader instance. The application experiences intermittent connection timeouts during peak traffic. The DB cluster parameter group has 'connect_timeout' set to 5 seconds. What should a database specialist recommend to reduce connection timeouts?

Accepted Answer

Enable RDS Proxy for the cluster.. Option B is correct because enabling RDS Proxy reduces connection overhead and provides a connection pool, mitigating timeouts. Option A is incorrect because increasing connect_timeout only delays the timeout, not the root cause. Option C is incorrect because adding readers does not help with writer connection timeouts. Option D is incorrect because the issue is not related to TLS.

Answer

Add additional reader instances to distribute the load.

Answer

Increase the 'connect_timeout' parameter to 10 seconds.

Answer

Enable IAM database authentication and require TLS.

Question 3

A data warehouse team is migrating from Amazon Redshift to Amazon Redshift RA3 nodes. The current cluster uses 10 DC2.large nodes. The new cluster will use 4 RA3.xlarge nodes. After the migration, the team notices that query performance is significantly slower. Which factor is the MOST likely cause of the performance degradation?

Accepted Answer

The cluster has fewer nodes, reducing parallelism.. Option A is correct because RA3 nodes use managed storage and compute is separate; fewer nodes reduce parallel processing capability. Option B is incorrect because RA3 nodes are designed for large data. Option C is incorrect because RA3 nodes have managed storage; disk space is not the issue. Option D is incorrect because the number of slices per node is lower in RA3, but the primary factor is fewer nodes.

Answer

The data distribution style is set to EVEN instead of KEY.

Answer

The cluster does not have enough disk space for the workload.

Answer

RA3 nodes are not optimized for large datasets.

Question 4

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. Which action can restore the table with minimal data loss?

Accepted Answer

Perform a point-in-time restore to a time just before the deletion.. Option B is correct because point-in-time recovery can restore to a time before the deletion. Option A is incorrect because restoring from the latest snapshot would lose transactions after the snapshot. Option C is incorrect because the table cannot be restored directly; the whole instance must be restored. Option D is incorrect because DMS is for migration, not recovery.

Answer

Use AWS Database Migration Service to replicate the table from another source.

Answer

Restore the DB instance from the latest automated snapshot.

Answer

Use the MySQL binary log to replay transactions up to the deletion.

Question 5

A company runs a critical Amazon DynamoDB table with on-demand capacity. The table experiences throttling errors (ProvisionedThroughputExceededException) during peak hours. The table has a global secondary index (GSI) with a different partition key. What is the MOST likely cause of the throttling?

Accepted Answer

The global secondary index is throttling due to uneven access patterns.. Option C is correct because on-demand tables can throttle if a GSI's write capacity is exceeded. Option A is incorrect because on-demand capacity scales automatically for the base table. Option B is incorrect because throttling is not due to read-heavy workloads on the base table. Option D is incorrect because partition keys are automatically managed.

Answer

The base table's write capacity is insufficient for the workload.

Answer

The partition key design causes hot partitions in the base table.

Answer

The table's read capacity is too low for the read-heavy workload.

Question 6

A company uses Amazon ElastiCache for Redis as a caching layer for a database. The cache cluster has one primary and one replica node. During a maintenance event, the primary node fails and the replica is promoted. After promotion, the application experiences increased latency. What should a database specialist do to reduce the impact of future failovers?

Accepted Answer

Enable cluster mode and distribute the cache across multiple shards.. Option D is correct because enabling Multi-AZ with automatic failover ensures a replica in a different AZ is promoted, but the key is to pre-warm the cache or use a larger instance. However, among the options, using a cluster mode with shards distributes load and reduces impact. Option A is incorrect because disabling replica reads doesn't help. Option B is incorrect because increasing replica count without cluster mode may not help. Option C is incorrect because automatic backup does not reduce latency after failover.

Answer

Disable replica reads to avoid stale data.

Answer

Enable automatic backups with a retention period of 35 days.

Answer

Add more replica nodes to the cluster.

Question 7

An Amazon RDS for SQL Server instance is running out of storage space. The instance uses 500 GB of Magnetic storage. The database specialist needs to increase storage to 1 TB with minimal downtime. Which solution meets these requirements?

Accepted Answer

Modify the DB instance and increase the allocated storage to 1 TB.. Option A is correct because RDS allows modifying storage with minimal downtime, though a brief outage may occur. Option B is incorrect because restoring from snapshot requires downtime. Option C is incorrect because converting storage type is a modification, not a separate process. Option D is incorrect because DMS is not needed.

Answer

Create a snapshot of the DB instance and restore it with larger storage.

Answer

Convert the storage type to General Purpose (gp2) and then increase size.

Answer

Use AWS DMS to migrate the database to a new instance with 1 TB storage.

Question 8

A company is using Amazon Neptune to run graph queries. The cluster has one writer and two reader instances. After a major version upgrade, the query performance degrades for complex traversal queries. The database specialist suspects that the query optimizer is not using indexes effectively. Which action should the specialist take to identify the issue?

Accepted Answer

Enable the Neptune explain plan feature and review the output.. Option C is correct because enabling the Neptune Query Language (SPARQL or Gremlin) explain plan can show how queries are executed and whether indexes are used. Option A is incorrect because instance metrics show system health, not query execution details. Option B is incorrect because removing indexes would worsen performance. Option D is incorrect because adding readers does not fix query optimization.

Answer

Drop and recreate all indexes to ensure they are up to date.

Answer

Add more reader instances to distribute the query load.

Answer

Check the CloudWatch metrics for CPU utilization and query latency.

Question 9

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size and has a high transaction rate. The migration must have minimal downtime. Which migration strategy should a database specialist recommend?

Accepted Answer

Use AWS DMS with ongoing replication to capture changes.. Option B is correct because AWS DMS with ongoing replication can minimize downtime by capturing changes. Option A is incorrect because native export/import requires downtime. Option C is incorrect because RMAN backup and restore requires downtime for restore. Option D is incorrect because copying dump files also requires downtime.

Answer

Copy the data files to Amazon S3 and then load into RDS.

Answer

Use Oracle Data Pump to export and import the database.

Answer

Perform an RMAN backup and restore to RDS.

Question 10

Which TWO of the following are valid methods to secure data at rest for an Amazon RDS for MySQL DB instance?

Accepted Answer

Enable encryption at rest using AWS KMS.. Option B (encryption at rest using AWS KMS) and Option C (enabling encryption when creating the instance) are correct. Option A is incorrect because SSL/TLS secures data in transit, not at rest. Option D is incorrect because RDS does not support Transparent Data Encryption (TDE) for MySQL. Option E is incorrect because RDS encryption is not enabled at the table level.

Answer

Enable SSL/TLS for connections to the DB instance.

Answer

Implement Transparent Data Encryption (TDE) using Oracle-compatible settings.

Answer

Use Amazon RDS encryption at the table level using the ENCRYPT option.

Question 11

Which THREE of the following are best practices for managing Amazon DynamoDB tables with provisioned throughput?

Accepted Answer

Use a composite key design with a sort key to enable efficient querying.. Options B, C, and D are correct. Option A is incorrect because adaptive capacity automatically handles uneven access patterns; manual partition splitting is not possible. Option E is incorrect because DynamoDB does not maintain indexes for all attributes; GSIs must be created explicitly.

Answer

Create a global secondary index on every attribute to support any query pattern.

Answer

Split hot partitions manually to distribute write traffic.

Question 12

Which TWO of the following are valid actions to take when an Amazon Redshift query is taking longer than expected due to disk-based operations?

Accepted Answer

Redistribute data across nodes using a distribution style that minimizes data movement.. Option A (increasing the number of nodes) and Option C (distributing data evenly) are correct. Option B is incorrect because Sort keys affect order, not disk spills. Option D is incorrect because WLM queues affect concurrency, not disk operations. Option E is incorrect because column compression reduces storage but may not reduce disk spills.

Answer

Use column compression to reduce the amount of data scanned.

Answer

Increase the number of workload management (WLM) query queues.

Answer

Change the sort keys to match the query's ORDER BY clause.

Question 13

A company's production RDS for PostgreSQL instance experienced a failover to the standby replica. After the failover, the application team reports that writes are failing with 'ReadOnlyException: Connection is read-only'. The DB instance status in the RDS console shows 'available'. Which action should the database administrator take to resolve the issue?

Accepted Answer

Update the application connection string to use the new writer endpoint from the RDS console.. Option B is correct because after a failover, the old primary becomes a standby and is read-only. The application must update its connection string to point to the new writer endpoint. Option A is wrong because rebooting forces another failover, not a resolution. Option C is wrong because modifying the DB instance does not change the endpoint. Option D is wrong because a read replica has a different use case.

Answer

Create a read replica and promote it to a new primary.

Answer

Reboot the DB instance to force a failover back to the original primary.

Answer

Modify the DB instance to enable Multi-AZ again.

Question 14

A database administrator notices that Amazon RDS for MySQL is experiencing high CPU utilization during peak hours. The application is read-heavy with many SELECT queries. Which action is most cost-effective to improve performance?

Accepted Answer

Create one or more read replicas and direct read traffic to them.. Option C is correct because read replicas offload read traffic from the primary, reducing CPU utilization. Option A is wrong because increasing instance size is more expensive and may not be optimal. Option B is wrong because vertical scaling is not the most cost-effective. Option D is wrong because adding storage does not reduce CPU.

Answer

Increase the DB instance class to a larger size.

Answer

Increase the allocated storage to improve I/O throughput.

Answer

Scale up the DB instance vertically to a higher vCPU count.

Question 15

A company is using Amazon DynamoDB with Auto Scaling enabled. During a flash sale, write traffic spikes and the application experiences ProvisionedThroughputExceededException errors. The DynamoDB table has provisioned write capacity of 1000 WCU and Auto Scaling is set to scale between 1000 and 10000 WCU. What is the most likely cause of the throttling?

Accepted Answer

Auto Scaling cannot react quickly enough to sudden traffic spikes.. Option D is correct because Auto Scaling reacts to actual consumption, but there is a lag; sudden spikes throttle before capacity increases. Option A is wrong because Auto Scaling does not have a maximum limit issue. Option B is wrong because throttling is due to write capacity, not partitioning. Option C is wrong because burst capacity is limited; sustained spikes require pre-warming or use of on-demand.

Answer

The DynamoDB table has insufficient partitions to handle the traffic.

Answer

The table's burst capacity is exhausted and Auto Scaling has not yet increased capacity.

Answer

The Auto Scaling policy has a maximum WCU limit that is too low.