Amazon DBS-C01 Online Practice Questions and Exam Preparation

Amazon DBS-C01 Online Questions & Answers

• Question 21:

  A business uses Amazon EC2 instances in VPC A to serve an internal file-sharing application. This application is supported by an Amazon ElastiCache cluster in VPC B that is peering with VPC A. The corporation migrates the instances of its applications from VPC A to VPC B. The file-sharing application is no longer able to connect to the ElastiCache cluster, as shown by the logs.

  What is the best course of action for a database professional to take in order to remedy this issue?

  A. Create a second security group on the EC2 instances. Add an outbound rule to allow traffic from the ElastiCache cluster security group.
  B. Delete the ElastiCache security group. Add an interface VPC endpoint to enable the EC2 instances to connect to the ElastiCache cluster.
  C. Modify the ElastiCache security group by adding outbound rules that allow traffic to VPC CIDR blocks from the ElastiCache cluster.
  D. Modify the ElastiCache security group by adding an inbound rule that allows traffic from the EC2 instances security group to the ElastiCache cluster.
  D. Modify the ElastiCache security group by adding an inbound rule that allows traffic from the EC2 instances security group to the ElastiCache cluster.

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  Explanation/Reference:

  https://docs.aws.amazon.com/vpc/latest/peering/vpc-peering-security- groups.html

• Question 22:

  Recently, a financial institution created a portfolio management service. The application's backend is powered by Amazon Aurora, which supports MySQL.

  The firm demands a response time of five minutes and a response time of five minutes. A database professional must create a disaster recovery system that is both efficient and has a low replication latency. How should the database professional tackle these requirements?

  A. Configure AWS Database Migration Service (AWS DMS) and create a replica in a different AWS Region.
  B. Configure an Amazon Aurora global database and add a different AWS Region.
  C. Configure a binlog and create a replica in a different AWS Region.
  D. Configure a cross-Region read replica.
  B. Configure an Amazon Aurora global database and add a different AWS Region.

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  Explanation/Reference:

  https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora- global-database-disaster-recovery.html https://aws.amazon.com/blogs/database/how-to-choose-the-best-disaster-recovery-option- for-your-amazon-aurora-mysql-cluster/ https://aws.amazon.com/about-aws/whats-new/2019/11/aurora-supports-in-place- conversion-to-global-database/

• Question 23:

  A company is using Amazon Redshift as its data warehouse solution. The Redshift cluster handles the following types of workloads:

  *Real-time inserts through Amazon Kinesis Data Firehose

  *Bulk inserts through COPY commands from Amazon S3

  *Analytics through SQL queries

  Recently, the cluster has started to experience performance issues.

  Which combination of actions should a database specialist take to improve the cluster's performance? (Choose three.)

  A. Modify the Kinesis Data Firehose delivery stream to stream the data to Amazon S3 with a high buffer size and to load the data into Amazon Redshift by using the COPY command.
  B. Stream real-time data into Redshift temporary tables before loading the data into permanent tables.
  C. For bulk inserts, split input files on Amazon S3 into multiple files to match the number of slices on Amazon Redshift. Then use the COPY command to load data into Amazon Redshift.
  D. For bulk inserts, use the parallel parameter in the COPY command to enable multi- threading.
  E. Optimize analytics SQL queries to use sort keys.
  F. Avoid using temporary tables in analytics SQL queries.
  B. Stream real-time data into Redshift temporary tables before loading the data into permanent tables.
  C. For bulk inserts, split input files on Amazon S3 into multiple files to match the number of slices on Amazon Redshift. Then use the COPY command to load data into Amazon Redshift.
  E. Optimize analytics SQL queries to use sort keys.

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  Explanation/Reference:

  https://aws.amazon.com/blogs/big-data/top-10-performance-tuning- techniques-for-amazon-redshift/

  Tip #6: Improving the efficiency of temporary tables

  Tip #9: Maintaining efficient data loads

  Amazon Redshift best practices suggest using the COPY command to perform data loads of file-based data.

  Tip #3: Sort key recommendation

  Sorting a table on an appropriate sort key can accelerate query performance, especially queries with range-restricted predicates, by requiring fewer table blocks to be read from disk.

• Question 24:

  A company has an existing system that uses a single-instance Amazon DocumentDB (with MongoDB compatibility) cluster. Read requests account for 75% of the system queries. Write requests are expected to increase by 50% after an upcoming global release. A database specialist needs to design a solution that improves the overall database performance without creating additional application overhead.

  Which solution will meet these requirements?

  A. Recreate the cluster with a shared cluster volume. Add two instances to serve both read requests and write requests.
  B. Add one read replica instance. Activate a shared cluster volume. Route all read queries to the read replica instance.
  C. Add one read replica instance. Set the read preference to secondary preferred.
  D. Add one read replica instance. Update the application to route all read queries to the read replica instance.
  C. Add one read replica instance. Set the read preference to secondary preferred.

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  Explanation/Reference:

  By default, an application directs its read operations to the primary member in a replica set (i.e. read preference mode "primary"). But, clients can specify a read preference to send read operations to secondaries. https://www.mongodb.com/

  docs/manual/core/read- preference/

  A read replica instance is an Amazon DocumentDB instance that supports only read operations. An Amazon DocumentDB cluster can have up to 15 replicas in addition to the primary instance. Having multiple replicas enables you to

  distribute read workloads and increase the read throughput of your cluster1.

  The read preference option determines how your MongoDB client or driver routes read requests to instances in your Amazon DocumentDB cluster. The secondary preferred option instructs the client to route read queries to the replicas,

  unless none are available, in which case the queries are routed to the primary instance2. This option can improve the overall database performance by offloading read requests from the primary instance, which handles all write requests, and

  balancing them across the replicas.

  Using this solution, the company can:

  Improve the overall database performance by adding one read replica instance and setting the read preference to secondary preferred. Avoid creating additional application overhead by using the built-in read preference capabilities of the

  MongoDB client or driver, without having to update the application code or connection string.

  Handle the expected increase in write requests by freeing up resources on the primary instance.

• Question 25:

  A company's Security department established new requirements that state internal users must connect to an existing Amazon RDS for SQL Server DB instance using their corporate Active Directory (AD) credentials. A Database Specialist must make the modifications needed to fulfill this requirement.

  Which combination of actions should the Database Specialist take? (Choose three.)

  A. Disable Transparent Data Encryption (TDE) on the RDS SQL Server DB instance.
  B. Modify the RDS SQL Server DB instance to use the directory for Windows authentication. Create appropriate new logins.
  C. Use the AWS Management Console to create an AWS Managed Microsoft AD. Create a trust relationship with the corporate AD.
  D. Stop the RDS SQL Server DB instance, modify it to use the directory for Windows authentication, and start it again. Create appropriate new logins.
  E. Use the AWS Management Console to create an AD Connector. Create a trust relationship with the corporate AD.
  F. Configure the AWS Managed Microsoft AD domain controller Security Group.
  B. Modify the RDS SQL Server DB instance to use the directory for Windows authentication. Create appropriate new logins.
  C. Use the AWS Management Console to create an AWS Managed Microsoft AD. Create a trust relationship with the corporate AD.
  F. Configure the AWS Managed Microsoft AD domain controller Security Group.

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  Explanation/Reference:

  https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_SQLServerWinAuth.ht ml

• Question 26:

  A company has a hybrid environment in which a VPC connects to an on-premises network through an AWS Site-to-Site VPN connection. The VPC contains an application that is hosted on Amazon EC2 instances. The EC2 instances run in

  private subnets behind an Application Load Balancer (ALB) that is associated with multiple public subnets. The EC2 instances need to securely access an Amazon DynamoDB table.

  Which solution will meet these requirements?

  A. Use the internet gateway of the VPC to access the DynamoDB table. Use the ALB to route the traffic to the EC2 instances.
  B. Add a NAT gateway in one of the public subnets of the VPC_ Configure the security groups of the EC2 instances to access the DynamoDB table through the NAT gateway
  C. Use the Site-to-Site VPN connection to route all DynamoD8 network traffic through the on-premises network infrastructure to access the EC2 instances
  D. Create a VPC endpoint for DynamoDB_ Assign the endpoint to the route table of the private subnets that contain the EC2 instances.
  D. Create a VPC endpoint for DynamoDB_ Assign the endpoint to the route table of the private subnets that contain the EC2 instances.

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  Explanation/Reference:

  Option D is correct because it meets the requirements of securely accessing a DynamoDB table from EC2 instances in a hybrid environment. A VPC endpoint for DynamoDB enables EC2 instances in a VPC to use their private IP addresses to access DynamoDB with no exposure to the public internet1. The EC2 instances do not require public IP addresses, and do not need an internet gateway, a NAT device, or a virtual private gateway in the VPC. The endpoint policy and the security groups of the EC2 instances can control access to DynamoDB. Traffic between the VPC and DynamoDB does not leave the Amazon network. Assigning the endpoint to the route table of the private subnets that contain the EC2 instances ensures that any requests to DynamoDB from those subnets are routed to the private endpoint within the Amazon network.

• Question 27:

  A Database Specialist migrated an existing production MySQL database from on-premises to an Amazon RDS for MySQL DB instance. However, after the migration, the database needed to be encrypted at rest using AWS KMS. Due to the size of the database, reloading, the data into an encrypted database would be too time- consuming, so it is not an option.

  How should the Database Specialist satisfy this new requirement?

  A. Create a snapshot of the unencrypted RDS DB instance. Create an encrypted copy of the unencrypted snapshot. Restore the encrypted snapshot copy.
  B. Modify the RDS DB instance. Enable the AWS KMS encryption option that leverages the AWS CLI.
  C. Restore an unencrypted snapshot into a MySQL RDS DB instance that is encrypted.
  D. Create an encrypted read replica of the RDS DB instance. Promote it the master.
  A. Create a snapshot of the unencrypted RDS DB instance. Create an encrypted copy of the unencrypted snapshot. Restore the encrypted snapshot copy.

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  Explanation/Reference:

  "However, because you can encrypt a copy of an unencrypted DB snapshot, you can effectively add encryption to an unencrypted DB instance. That is, you can create a snapshot of your DB instance, and then create an encrypted copy of that snapshot. You can then restore a DB instance from the encrypted snapshot, and thus you have an encrypted copy of your original DB instance. For more information, see Copying a Snapshot." https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Overview.Encryption.html

• Question 28:

  A financial company has allocated an Amazon RDS MariaDB DB instance with large storage capacity to accommodate migration efforts. Post-migration, the company purged unwanted data from the instance. The company now want to

  downsize storage to save money. The solution must have the least impact on production and near-zero downtime.

  Which solution would meet these requirements?

  A. Create a snapshot of the old databases and restore the snapshot with the required storage
  B. Create a new RDS DB instance with the required storage and move the databases from the old instances to the new instance using AWS DMS
  C. Create a new database using native backup and restore
  D. Create a new read replica and make it the primary by terminating the existing primary
  B. Create a new RDS DB instance with the required storage and move the databases from the old instances to the new instance using AWS DMS

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  Explanation/Reference:

  https://aws.amazon.com/premiumsupport/knowledge-center/rds-db-storage- size/ Use AWS Database Migration Service (AWS DMS) for minimal downtime.

• Question 29:

  A database specialist at a large multi-national financial company is in charge of designing the disaster recovery strategy for a highly available application that is in development. The application uses an Amazon DynamoDB table as its data store. The application requires a recovery time objective (RTO) of 1 minute and a recovery point objective (RPO) of 2 minutes.

  Which operationally efficient disaster recovery strategy should the database specialist recommend for the DynamoDB table?

  A. Create a DynamoDB stream that is processed by an AWS Lambda function that copies the data to a DynamoDB table in another Region.
  B. Use a DynamoDB global table replica in another Region. Enable point-in-time recovery for both tables.
  C. Use a DynamoDB Accelerator table in another Region. Enable point-in-time recovery for the table.
  D. Create an AWS Backup plan and assign the DynamoDB table as a resource.
  C. Use a DynamoDB Accelerator table in another Region. Enable point-in-time recovery for the table.

• Question 30:

  A company is using Amazon with Aurora Replicas for read-only workload scaling. A Database Specialist needs to split up two read-only applications so each application always connects to a dedicated replica. The Database Specialist wants to implement load balancing and high availability for the read-only applications.

  Which solution meets these requirements?

  A. Use a specific instance endpoint for each replica and add the instance endpoint to each read-only application connection string.
  B. Use reader endpoints for both the read-only workload applications.
  C. Use a reader endpoint for one read-only application and use an instance endpoint for the other read-only application.
  D. Use custom endpoints for the two read-only applications.
  D. Use custom endpoints for the two read-only applications.

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  Explanation/Reference:

  https://aws.amazon.com/about-aws/whats-new/2018/11/amazon-aurora-simplifies- workload-management-with-custom-endpoints/