Instant Access Amazon.DBS-C01.v2024-06-20.q110 Actual Practice Test Engine for Free (Page 18)

Question 81

A company is using an Amazon Aurora PostgreSQL DB cluster for the backend of its mobile application. The application is running continuously and a database specialist is satisfied with high availability and fast failover, but is concerned about performance degradation after failover.
How can the database specialist minimize the performance degradation after failover?

A.Enable cluster cache management for the Aurora DB cluster and set the promotion priority for the writer DB instance and replica to tier-0
B.Enable cluster cache management tor the Aurora DB cluster and set the promotion priority for the writer DB instance and replica to tier-1
C.Enable Query Plan Management for the Aurora DB cluster and perform a manual plan capture
D.Enable Query Plan Management for the Aurora DB cluster and force the query optimizer to use the desired plan

Correct Answer: A

Explanation from Amazon documents:
Amazon Aurora PostgreSQL supports cluster cache management, which is a feature that helps reduce the impact of failover on query performance by preserving the cache of the primary DB instance on one or more Aurora Replicas. Cluster cache management allows you to assign a promotion priority tier to each DB instance in your Aurora DB cluster. The promotion priority tier determines the order in which Aurora Replicas are considered for promotion to the primary instance after a failover. The lower the numerical value of the tier, the higher the priority.
By enabling cluster cache management for the Aurora DB cluster and setting the promotion priority for the writer DB instance and replica to tier-0, the database specialist can minimize the performance degradation after failover. This solution will ensure that the primary DB instance and one Aurora Replica have the same cache contents and are in the same promotion priority tier. In the event of a failover, Aurora will promote the tier-0 replica to the primary role, and the cache will be preserved. This will reduce the number of cache misses and improve query performance after failover.
Therefore, option A is the correct solution to minimize the performance degradation after failover. Option B is incorrect because setting the promotion priority for the writer DB instance and replica to tier-1 will not preserve the cache after failover. Aurora will first try to promote a tier-0 replica, which may have a different cache than the primary instance. Option C is incorrect because enabling Query Plan Management and performing a manual plan capture will not affect the cache behavior after failover. Query Plan Management is a feature that helps you control query execution plans and improve query performance by creating and enforcing custom execution plans. Option D is incorrect because enabling Query Plan Management and forcing the query optimizer to use the desired plan will not affect the cache behavior after failover. Forcing the query optimizer to use a desired plan may improve query performance by avoiding suboptimal plans, but it will not prevent cache misses after failover.

Question 82

A company is load testing its three-tier production web application deployed with an AWS CloudFormation template on AWS. The Application team is making changes to deploy additional Amazon EC2 and AWS Lambda resources to expand the load testing capacity. A Database Specialist wants to ensure that the changes made by the Application team will not change the Amazon RDS database resources already deployed.
Which combination of steps would allow the Database Specialist to accomplish this? (Choose two.)

A.Review the stack drift before modifying the template
B.Create and review a change set before applying it
C.Export the database resources as stack outputs
D.Define the database resources in a nested stack
E.Set a stack policy for the database resources

Question 83

A pharmaceutical company uses Amazon Quantum Ledger Database (Amazon QLDB) to store its clinical trial data records. The company has an application that runs as AWS Lambda functions. The application is hosted in the private subnet in a VPC.
The application does not have internet access and needs to read some of the clinical data records. The company is concerned that traffic between the QLDB ledger and the VPC could leave the AWS network. The company needs to secure access to the QLDB ledger and allow the VPC traffic to have read-only access.
Which security strategy should a database specialist implement to meet these requirements?

A.Move the QLDB ledger into a private database subnet inside the VPC. Run the Lambda functions inside the same VPC in an application private subnet. Ensure that the VPC route table allows read-only flow from the application subnet to the database subnet.
B.Create an AWS PrivateLink VPC endpoint for the QLDB ledger. Attach a VPC policy to the VPC endpoint to allow read-only traffic for the Lambda functions that run inside the VPC.
C.Add a security group to the QLDB ledger to allow access from the private subnets inside the VPC where the Lambda functions that access the QLDB ledger are running.
D.Create a VPN connection to ensure pairing of the private subnet where the Lambda functions are running with the private subnet where the QLDB ledger is deployed.

Question 84

A financial services company is developing a shared data service that supports different applications from throughout the company. A Database Specialist designed a solution to leverage Amazon ElastiCache for Redis with cluster mode enabled to enhance performance and scalability. The cluster is configured to listen on port
6379.
Which combination of steps should the Database Specialist take to secure the cache data and protect it from unauthorized access? (Choose three.)

A.Enable in-transit and at-rest encryption on the ElastiCache cluster.
B.Ensure that Amazon CloudWatch metrics are configured in the ElastiCache cluster.
C.Ensure the security group for the ElastiCache cluster allows all inbound traffic from itself and inbound traffic on TCP port 6379 from trusted clients only.
D.Create an IAM policy to allow the application service roles to access all ElastiCache API actions.
E.Ensure the security group for the ElastiCache clients authorize inbound TCP port 6379 and port 22 traffic from the trusted ElastiCache cluster's security group.
F.Ensure the cluster is created with the auth-token parameter and that the parameter is used in all subsequent commands.

Question 85

A Database Specialist is troubleshooting an application connection failure on an Amazon Aurora DB cluster with multiple Aurora Replicas that had been running with no issues for the past 2 months. The connection failure lasted for 5 minutes and corrected itself after that. The Database Specialist reviewed the Amazon RDS events and determined a failover event occurred at that time. The failover process took around 15 seconds to complete.
What is the MOST likely cause of the 5-minute connection outage?

A.After a database crash, Aurora needed to replay the redo log from the last database checkpoint
B.The client-side application is caching the DNS data and its TTL is set too high
C.After failover, the Aurora DB cluster needs time to warm up before accepting client connections
D.There were no active Aurora Replicas in the Aurora DB cluster

Question 81

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Question 83

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Question 85

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