DBS-C01 Practice Exam 57 — 20 Questions

Question 1

A company is migrating its on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size and has a 24-hour maintenance window. The company needs to minimize downtime during the migration. Which AWS service should be used to perform the migration with minimal downtime?

Accepted Answer

AWS Database Migration Service (AWS DMS). AWS DMS supports homogeneous and heterogeneous migrations with minimal downtime by replicating ongoing changes. RDS for Oracle does not support native Oracle Data Guard (B) across environments. AWS SCT (C) is for schema conversion, not full data migration. AWS Database Migration Service (D) is the recommended service, but option A is AWS DMS which is correct.

Answer

AWS Database Migration Service

Answer

Oracle Data Guard

Answer

AWS Schema Conversion Tool (AWS SCT)

Question 2

A company is running an Amazon RDS for MySQL Multi-AZ DB instance. The company wants to implement a backup strategy that meets a recovery point objective (RPO) of 5 minutes and a recovery time objective (RTO) of 1 hour. Which THREE steps should the company take to meet these objectives?

Accepted Answer

Configure AWS Backup to copy automated backups to another region.. Automated backups with a retention period of 35 days provide point-in-time recovery. Cross-region snapshots via AWS Backup provide additional protection. A read replica can be promoted quickly for failover. Option A (daily manual snapshots) may not meet the 5-minute RPO. Option D (single-AZ) is not as resilient. The correct options are B, C, and E.

Answer

Change the DB instance to a Single-AZ configuration to reduce costs.

Answer

Take daily manual snapshots and copy them to another region.

Question 3

A company is using Amazon DynamoDB with auto scaling enabled. The table's write capacity is set to a minimum of 50 and maximum of 500 write capacity units (WCUs). The actual consumed write capacity is consistently at 100 WCUs. What should the database specialist do to optimize costs without impacting performance?

Accepted Answer

Lower the minimum write capacity to 100 WCUs.. Option A is correct because lowering the minimum to 100 WCUs matches the actual usage, preventing over-provisioning. Option B is wrong because decreasing the maximum could cause throttling during spikes. Option C is wrong because increasing the minimum would increase costs. Option D is wrong because disabling auto scaling would require manual management.

Answer

Increase the minimum write capacity to 200 WCUs.

Answer

Disable auto scaling and set the write capacity to 100 WCUs.

Answer

Decrease the maximum write capacity to 200 WCUs.

Question 4

A company is running an Amazon RDS for SQL Server DB instance. The database administrator needs to perform a major version upgrade. What is the recommended approach to minimize downtime?

Accepted Answer

Create a Read Replica of the DB instance with the new version, promote it to a standalone instance, and then redirect application traffic.. Option C is correct because creating a Read Replica with the new version, promoting it, and then redirecting traffic minimizes downtime. Option A is incorrect because modifying the DB instance directly causes downtime during the upgrade. Option B is incorrect because taking a snapshot and restoring takes time and causes downtime. Option D is incorrect because AWS DMS can migrate with minimal downtime, but it is more complex and not the standard recommended approach for version upgrades.

Answer

Use AWS Database Migration Service (DMS) to migrate the database to a new instance with the new version.

Answer

Take a snapshot of the DB instance and restore it with the new version.

Answer

Modify the DB instance directly and apply the new version during the maintenance window.

Question 5

A company runs an Amazon RDS for MySQL Multi-AZ DB instance. The application experiences intermittent read latency spikes. The DB instance type is db.r5.large with 500 GB of General Purpose SSD (gp2) storage. The spike occurs during peak hours when read activity is high. Which action would most effectively reduce read latency?

Accepted Answer

Create an Amazon RDS read replica and direct read traffic to it.. Option D is correct. Adding a read replica offloads read traffic from the primary instance, reducing latency. Option A is wrong because Multi-AZ does not improve read performance; the standby is not used for reads. Option B is wrong because increasing storage may improve throughput but not resolve read contention. Option C is wrong because gp3 provides consistent performance but does not solve read scaling.

Answer

Change the storage type to Provisioned IOPS (io1).

Answer

Enable Multi-AZ with a standby replica.

Answer

Increase the allocated storage to 1 TB to improve IOPS.

Question 6

A company is planning to migrate its on-premises Oracle database to Amazon RDS for Oracle. The database uses Oracle Data Guard for disaster recovery. Which TWO AWS services can be used to assess the database and plan the migration? (Choose TWO.)

Accepted Answer

AWS Database Migration Service (DMS). Option C and Option D are correct. AWS DMS can migrate the database, and AWS Schema Conversion Tool (SCT) can assess and convert the schema. Option A is wrong because CloudEndure is for server migration. Option B is wrong because AWS Migration Hub tracks migrations but does not assess databases. Option E is wrong because AWS Snowball is for large data transfer offline.

Answer

AWS Migration Hub

Answer

CloudEndure Disaster Recovery

Answer

AWS Snowball

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 has an Amazon Aurora MySQL DB cluster with a single writer and two readers. The writer instance fails, and the failover mechanism promotes one of the readers to writer. The application, which uses a custom connection pool, continues to experience errors for several minutes. What should the database administrator do to minimize downtime during future failovers?

Accepted Answer

Modify the application to use the cluster endpoint instead of the instance endpoint.. Option B is correct because using the cluster endpoint ensures automatic routing to the current writer. Option A is wrong because DNS caching is fixed by using cluster endpoint. Option C is wrong because increasing pool reduces latency but not failover detection. Option D is wrong because Multi-AZ is already used.

Answer

Increase the connection pool size to handle more connections.

Answer

Configure the application to use the reader endpoint for all traffic.

Answer

Enable Multi-AZ on the Aurora cluster.

Question 9

A company has a production Amazon RDS for PostgreSQL Multi-AZ DB instance. The company's security team requires that all database connections use IAM database authentication. The company also needs to ensure that connections from a specific application server are allowed only if the server has a valid IAM role. Which combination of steps should the database administrator take to meet these requirements?

Accepted Answer

Enable IAM database authentication on the RDS instance. Create a database user that matches the IAM role ARN. Grant the application server's IAM role the rds_iam role. Configure the application to generate an authentication token using the IAM role's credentials.. IAM database authentication requires mapping IAM users/roles to database users and enforcing SSL. Steps: 1) Enable IAM DB authentication on the RDS instance. 2) Create a database user that matches the IAM role ARN. 3) Grant the application server's IAM role permission to connect. 4) Configure the application to use an authentication token. The correct answer is A because it includes enabling IAM auth, creating the database user, and configuring the application. Option B is wrong because it uses the IAM user ARN instead of the role ARN. Option C is wrong because it does not enable IAM auth. Option D is wrong because it uses a password.

Answer

Create a database user with a strong password. Enable IAM database authentication. Assign the application server an IAM policy that allows rds-db:connect. Configure the application to use the password.

Answer

Enable IAM database authentication. Create a database user matching the IAM user ARN. Grant the application server's IAM user the rds_iam role. Configure the application to use an authentication token.

Answer

Enable IAM database authentication. Create a database user that matches the IAM role ARN. Configure the application to use the database master username and password.

Question 10

A company is running an Amazon RDS for MySQL Multi-AZ DB instance. They notice increased latency during peak hours. The DB instance type is db.r5.large, and the storage is General Purpose SSD (gp2) with 500 GB. The application is read-heavy with frequent SELECT queries. Which action would most likely resolve the latency issue without changing the DB instance class?

Accepted Answer

Create an Amazon RDS read replica in the same region.. Option B is correct because adding a read replica offloads read traffic from the primary instance, reducing latency. Option A is wrong because Multi-AZ is for high availability, not read scaling. Option C is wrong because increasing storage size may improve IOPS but does not directly address read load. Option D is wrong because enabling Performance Insights is for monitoring, not performance improvement.

Answer

Enable Performance Insights and analyze queries.

Answer

Enable Multi-AZ on the existing DB instance.

Answer

Increase the allocated storage to 1,000 GB.

Question 11

A company is using Amazon RDS for SQL Server with Always On Availability Groups. The primary DB instance is in us-east-1, and the secondary is in us-west-2. The application writes to the primary and reads from the secondary. The secondary instance becomes unreachable due to a network issue. What happens to the primary instance?

Accepted Answer

The primary continues to accept read and write operations.. Option A is correct because the primary continues to accept writes independently; the secondary failure does not affect primary operations. Option B is wrong because failover is not automatic for read replicas. Option C is wrong because the primary does not become read-only. Option D is wrong because write operations continue.

Answer

The primary stops accepting write operations.

Answer

The primary automatically fails over to the secondary.

Answer

The primary becomes read-only until the secondary is restored.

Question 12

A company is using Amazon DynamoDB for a web application. The company notices that read requests to a particular table are throttled during peak hours. The table has a provisioned read capacity of 1000 read capacity units (RCUs). The read requests are mostly eventually consistent reads. What should the company do to reduce throttling without changing the application code?

Accepted Answer

Increase the provisioned read capacity for the table.. Increasing the provisioned read capacity directly addresses throttling by allowing more reads per second. Option B is wrong because DynamoDB Accelerator (DAX) requires code changes to use. Option C is wrong because eventually consistent reads are already used. Option D is wrong because using strongly consistent reads would increase RCU consumption, worsening throttling.

Answer

Use Amazon ElastiCache to cache the read results.

Answer

Switch to strongly consistent reads to reduce the number of read requests.

Answer

Implement DynamoDB Accelerator (DAX) to cache read requests.

Question 13

An administrator is troubleshooting a permissions issue. A user with the IAM policy shown is unable to share an automated system snapshot with another AWS account. Which action should the administrator take to resolve this issue?

Accepted Answer

Change the Resource to "arn:aws:rds:us-east-1:123456789012:snapshot:automated:*".. Option C is correct because the policy allows actions on DB snapshots, but automated snapshots have the resource type 'automated-snapshot' and require explicit resource ARN instead of '*'. Option A is wrong because the policy already includes the necessary actions. Option B is wrong because the issue is not about cross-region copying. Option D is wrong because the issue is not about manual snapshots.

Answer

Add the rds:ModifyDBSnapshotAttribute action to the policy.

Answer

Add the rds:CopyDBSnapshot action for cross-region copy.

Answer

Change the Resource to "arn:aws:rds:us-east-1:123456789012:snapshot:rds:*".

Question 14

A company is migrating a 5 TB MySQL database to Amazon Aurora MySQL. The migration must have minimal downtime and support ongoing replication. The source database is in a corporate data center with a 500 Mbps internet connection. Which THREE steps should the database specialist take?

Accepted Answer

Use AWS Schema Conversion Tool (AWS SCT) to convert the schema.. Options A, C, and E are correct. Option A: AWS DMS with CDC allows ongoing replication with minimal downtime. Option C: Using AWS SCT helps convert the schema if needed. Option E: Using an AWS Snowball Edge device for initial load reduces the time for large data transfer over slow internet. Option B is wrong because a VPN alone does not migrate data. Option D is wrong because a read replica is not a migration tool; it is a feature of Aurora.

Answer

Establish a VPN connection to AWS and use mysqldump.

Answer

Create an Aurora read replica from the source database.

Question 15

A company is using Amazon DynamoDB with on-demand capacity. The operations team notices that the number of throttled write requests has increased. Which metric should be monitored to determine if the table's write capacity is being exceeded?

Accepted Answer

WriteThrottleEvents. Option D is correct because 'WriteThrottleEvents' directly indicates throttled writes. Option A is wrong because 'ConsumedWriteCapacityUnits' shows actual usage, not throttling. Option B is wrong because 'ProvisionedWriteCapacityUnits' is not applicable for on-demand. Option C is wrong because 'ThrottledWriteRequests' is not a standard CloudWatch metric name (the correct name is WriteThrottleEvents).

Answer

ThrottledWriteRequests

Answer

ProvisionedWriteCapacityUnits

Answer

ConsumedWriteCapacityUnits

Question 16

A company uses Amazon DynamoDB with On-Demand capacity for a gaming application. During a new game launch, write traffic spikes 10x normal for 30 minutes. Some write requests receive ProvisionedThroughputExceeded exceptions. What is the MOST likely cause and solution?

Accepted Answer

The partition key is not distributing writes evenly, causing a hot partition. Redesign the partition key for uniform access.. On-Demand capacity can handle spikes but has per-partition throughput limits. If a hot partition exists, writes to that partition may exceed its limit. Option A is correct because uneven partition keys cause throttling. Option B is incorrect because On-Demand does not have table-level limits. Option C is not the primary cause. Option D is incorrect as GSI writes also consume write capacity.

Answer

On-Demand capacity cannot handle sudden spikes. Switch to Provisioned capacity with auto scaling.

Answer

DynamoDB Streams is enabled, causing additional write throttling. Disable streams.

Answer

The table has a global secondary index with a different partition key that is unevenly accessed. Remove the GSI.

Question 17

A company runs an Amazon ElastiCache for Redis cluster as a caching layer for a high-traffic web application. The cluster has one primary and two replica nodes. Recently, the application experienced increased latency. Monitoring shows that the CPU utilization of the primary node is consistently above 80%, while replicas are below 40%. The application uses the cluster mode disabled. The operations team needs to reduce the CPU load on the primary node. Which solution should they implement?

Accepted Answer

Configure the application to use read replicas for read queries by using the reader endpoint.. Offloading read traffic to replicas reduces primary CPU. Enabling cluster mode allows sharding writes. Option A is correct because using replicas for reads distributes read load. Option B (scaling vertically) may help but is costly. Option C (read-through cache) does not reduce primary writes. Option D (increase replicas) does not help if reads are not directed to replicas.

Answer

Implement a read-through cache pattern using DynamoDB Accelerator (DAX).

Answer

Upgrade the primary node to a larger instance type.

Answer

Add more replica nodes to the cluster.

Question 18

A company is using Amazon DynamoDB with on-demand capacity mode. The company notices that during a flash sale, the write requests are throttled. What is the most likely cause of the throttling?

Accepted Answer

A hot partition is causing throttling even though the table uses on-demand capacity.. On-demand tables have a per-table throughput limit that can be exceeded, especially during a flash sale. Option A (WCU limit) does not apply to on-demand. Option B (partition hot spot) could cause throttling even in on-demand if a single partition is overloaded. Option C (table limit) is correct, but partition hot spots are a common cause. The best answer is B because on-demand automatically scales but can still throttle if a partition is hot.

Answer

The table has reached its maximum throughput limit for on-demand mode.

Answer

The table is not configured for auto scaling.

Answer

The provisioned write capacity units (WCUs) are set too low.

Question 19

A company is migrating an on-premises Oracle database to Amazon RDS for Oracle. The database is 2 TB in size and has a 24/7 uptime requirement. The migration must have minimal downtime and support ongoing replication. Which THREE services or features should the specialist use to accomplish this?

Accepted Answer

An AWS DMS replication instance.. Options A, B, and D are correct. Option A: AWS DMS can perform ongoing replication with change data capture. Option B: AWS SCT helps convert the schema. Option D: A replication instance is required for DMS. Option C is wrong because RDS Oracle does not support cross-region automated backups as a migration tool. Option E is wrong because RDS Oracle does not support native Oracle Data Guard for cross-region replication.

Answer

Oracle Data Guard to replicate to RDS.

Answer

Amazon RDS cross-Region automated backups.

Question 20

A company is using Amazon DynamoDB with auto scaling enabled. The table's read capacity is set to a minimum of 100 and maximum of 1000 read capacity units (RCUs). The actual consumed read capacity is consistently at 200 RCUs. What should the database specialist do to optimize costs without impacting performance?

Accepted Answer

Lower the minimum read capacity to 200 RCUs.. Option A is correct because lowering the minimum to 200 RCUs ensures auto scaling does not scale below the actual usage, reducing provisioned capacity costs. Option B is wrong because decreasing the maximum could cause throttling during spikes. Option C is wrong because increasing the minimum would increase costs unnecessarily. Option D is wrong because disabling auto scaling would require manual management and may lead to over-provisioning.

Answer

Decrease the maximum read capacity to 500 RCUs.

Answer

Disable auto scaling and set the read capacity to 200 RCUs.

Answer

Increase the minimum read capacity to 500 RCUs.