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

Question 1

Refer to the exhibit. A database administrator runs the AWS CLI command to retrieve CloudWatch metrics for an Amazon RDS DB instance. The output shows a spike in WriteLatency at 10:05 UTC. What is the most likely cause of this spike?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The DB instance's gp2 volume has exhausted its burst credits.. A sudden spike in write latency often indicates that the storage volume has exhausted its burst credits and is now using baseline performance, which may be slower. Option B is incorrect because taking a snapshot causes I/O suspension, not necessarily a latency spike. Option C is incorrect because a large number of concurrent connections typically causes increased CPU and memory usage, not a latency spike. Option D is incorrect because a Multi-AZ failover would cause a brief downtime, not a latency spike.

Answer

The DB instance is in the process of taking a snapshot.

Answer

There is a large number of concurrent connections to the DB instance.

Answer

The DB instance experienced a Multi-AZ failover.

Question 2

A developer accidentally deleted a production RDS for PostgreSQL DB instance. The company has automated backups enabled with a retention period of 7 days. What is the fastest way to restore the database to the state just before the deletion?

Accepted Answer

Create a new DB instance and use point-in-time recovery to the time just before deletion.. When automated backups are enabled, you can perform point-in-time recovery (PITR) to restore the database to any point within the retention period, including just before deletion. RDS retains the automated backups and transaction logs for the retention period even after the instance is deleted. Option A is incorrect because Amazon RDS does not use a Recycle Bin for DB instances. Option B is incorrect because restoring from the latest automated snapshot would not recover transactions after that snapshot; you need PITR to get the state just before deletion. Option C is incorrect because AWS DMS is for migrating data between databases, not for recovering a deleted instance.

Answer

Recover the instance from the Amazon RDS Recycle Bin.

Answer

Restore from the latest automated snapshot that was taken before deletion.

Answer

Use the AWS DMS to migrate the data from the deleted instance to a new one.

Question 3

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.. Adding an RDS read replica offloads read traffic from the primary DB instance, reducing read contention and latency. Option A is incorrect because changing to io1 improves I/O performance but does not address read contention from high read load on the primary. Option B is incorrect because Multi-AZ provides high availability but the standby replica does not serve read traffic. Option C is incorrect because increasing storage increases baseline IOPS but does not offload read operations.

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 4

Refer to the exhibit. An Amazon RDS for Oracle instance is experiencing ORA-00257 errors. The DBA has already increased the archive log retention setting. What is the most efficient next step to resolve the issue without manual intervention?

Accepted Answer

Modify the DB instance to increase the allocated storage.. The ORA-00257 error indicates the flash recovery area is full. In Amazon RDS for Oracle, the flash recovery area size is tied to the allocated storage (default is 30% of allocated storage). Increasing allocated storage automatically expands the recovery area, resolving the issue without manual intervention. Option A is incorrect because Amazon RDS for Oracle does not support archiving redo logs directly to Amazon S3 as a built-in feature. Option B is incorrect because rebooting the DB instance does not free space in the recovery area; it only restarts the database. Option D is incorrect because manually deleting archive logs using RMAN requires manual intervention, which is not the most efficient automated solution.

Answer

Configure archiving to Amazon S3 to offload logs.

Answer

Reboot the DB instance to clear the recovery area.

Answer

Manually delete old archive logs from the recovery area using RMAN.

Question 5

A company is using Amazon DynamoDB with on-demand capacity. The application experiences increased latency during peak hours. The DynamoDB table receives about 5,000 writes per second and 10,000 reads per second. The read latency is high, but write latency is acceptable. What should the company do to reduce read latency?

Accepted Answer

Enable DynamoDB Accelerator (DAX) for the table.. DynamoDB Accelerator (DAX) is a fully managed, highly available, in-memory cache that significantly reduces read latency for DynamoDB tables, especially for repeated reads. DAX allows you to offload read traffic from the table and serve read requests from the cache, reducing the load on the table and improving response times. Option A is wrong because DynamoDB Streams is used to capture changes to items in the table, not to cache data or offload read traffic. Option B is wrong because DynamoDB does not support read replicas; DAX is the caching solution for reads. Option D is wrong because switching to provisioned capacity and enabling auto scaling would help with scaling write capacity but does not directly address high read latency; DAX is specifically designed for in-memory caching to improve read performance.

Answer

Enable DynamoDB Streams to offload read traffic.

Answer

Create a read replica of the DynamoDB table.

Answer

Switch to provisioned capacity and enable auto scaling.

Question 6

A company manages multiple RDS for PostgreSQL instances in different AWS accounts. The security team requires that all DB instances have automated backups enabled with a retention period of at least 14 days. How can the company enforce this policy across all accounts?

Accepted Answer

Use AWS Config rules to evaluate and auto-remediate non-compliant instances.. AWS Config with managed rules can evaluate RDS instances and enforce backup settings. Option A is wrong because CloudTrail only logs API calls for auditing, it does not enforce configuration. Option B is wrong because Service Control Policies (SCPs) restrict permissions at the organization level but cannot directly require backup retention on resources. Option C is wrong because IAM policies can control permissions to create instances but cannot enforce backup retention settings on existing instances; they can deny creation if certain conditions are not met, but that is not as comprehensive as AWS Config auto-remediation.

Answer

Use AWS CloudTrail to monitor backup settings and alert on non-compliance.

Answer

Apply a service control policy (SCP) that requires backup retention.

Answer

Create an IAM policy that denies creating DB instances without backup retention.

Question 7

Refer to the exhibit. An application on an EC2 instance is trying to read an object from the S3 bucket 'data-lake-prod'. The instance is in a VPC with an IP address of 10.0.1.5. The application receives an Access Denied error. What is the cause?

Accepted Answer

A Deny statement with a source IP condition is blocking access.. The Deny statement applies to the source IP 10.0.1.5 (within 10.0.0.0/8), overriding the Allow. Option A is wrong because the IAM role does allow s3:GetObject on the bucket. Option C is wrong because there is no explicit condition on the Allow statement. Option D is wrong because the policy is attached to the role, not an SCP.

Answer

An SCP is denying S3 access to the account.

Answer

The S3 bucket policy requires a specific VPC endpoint.

Answer

The IAM role does not have permission to read from the bucket.

Question 8

A company is running an Amazon Aurora MySQL-compatible edition DB cluster. The application reports that a recent schema change caused a significant increase in the number of deadlocks. Which parameter should the DBA check and possibly adjust to reduce deadlocks?

Accepted Answer

transaction_isolation. Adjusting the transaction isolation level can reduce deadlocks by decreasing the locking overhead. For example, using READ COMMITTED instead of REPEATABLE READ reduces the use of gap locks, which are a common source of deadlocks. Option A, innodb_lock_wait_timeout, determines how long a transaction waits for a lock before timing out; it does not prevent deadlocks but rather handles lock waits. Option B, autocommit, affects when transactions are committed but does not directly impact deadlock occurrence. Option C, max_connections, limits concurrent connections, which can reduce overall contention but is not a direct deadlock reduction parameter.

Answer

innodb_lock_wait_timeout

Answer

autocommit

Answer

max_connections

Question 9

A company uses Amazon ElastiCache for Redis to cache frequently accessed data. The cache cluster experiences high CPU utilization during peak hours. The cluster has a single node of type cache.r5.large. What is the most cost-effective way to reduce CPU utilization while maintaining performance?

Accepted Answer

Add a read replica to distribute read traffic.. Adding a read replica distributes read traffic away from the primary node, reducing its CPU utilization. This is more cost-effective than upgrading to a larger instance type (option B) because you can add a smaller replica node. Option A (enabling encryption) does not reduce CPU utilization and adds overhead. Option D (changing maxmemory-policy) also does not reduce CPU utilization.

Answer

Enable encryption at rest and in transit.

Answer

Upgrade to a cache.r5.xlarge node type.

Answer

Increase the maxmemory-policy parameter to 'allkeys-lru'.

Question 10

A company's RDS for SQL Server instance has been running for 3 years. The DBA notices that the DB instance's allocated storage (500 GB) is 80% full. The application is write-heavy. The DBA needs to increase storage without downtime. What is the most efficient way to achieve this?

Accepted Answer

Use the Modify DB Instance API to increase allocated storage.. RDS for SQL Server supports modifying storage online using the Modify DB Instance API without downtime. Option A is incorrect because you cannot attach additional EBS volumes directly to an RDS instance; RDS manages its own storage. Option B is incorrect because creating a new instance and migrating data would require downtime. Option C is incorrect because taking a snapshot and restoring a new instance also incurs downtime and is less efficient than modifying storage in place.

Answer

Attach an additional EBS volume to the DB instance.

Answer

Create a new DB instance with larger storage and migrate data.

Answer

Take a snapshot and restore a new instance with larger storage.

Question 11

A company is using Amazon RDS for MySQL with Multi-AZ deployment. The DBA receives an alert that the standby replica is lagging behind the primary. Which TWO actions should the DBA take to investigate the issue? (Choose TWO.)

Accepted Answer

Verify network latency between the primary and standby.. The correct answers are B and C. In Amazon RDS Multi-AZ deployments, the standby replica is synchronously replicated from the primary, and the 'ReplicaLag' metric in CloudWatch is used to monitor the replication delay. Checking this metric (option C) helps identify lag. Additionally, verifying network latency between the primary and standby (option B) can uncover connectivity issues causing lag. Option A is incorrect because Multi-AZ does not have read replicas; Read Replicas are separate from the Multi-AZ standby. Option D is incorrect because storage size does not directly affect replication lag. Option E is incorrect because Multi-AZ uses synchronous replication, and changing to asynchronous would not solve the issue and is not a supported change for Multi-AZ.

Answer

Check the 'Replica Lag' metric for any read replicas.

Answer

Increase the allocated storage to improve IOPS.

Answer

Change the replication type from asynchronous to synchronous.

Question 12

A company uses Amazon DynamoDB with provisioned capacity for a critical application. During a traffic spike, the table experiences throttling on write requests. The DBA needs to resolve the issue quickly. Which THREE actions should the DBA take? (Choose THREE.)

Accepted Answer

Implement exponential backoff in the application's write requests.. Uses exponential backoff to handle throttling by retrying requests with increasing delays. Option C temporarily increases write capacity units (WCU) to handle the spike. Option D enables auto scaling to automatically adjust capacity. Option A is incorrect because switching to on-demand may resolve throttling but is not one of the three correct actions; the question asks for three specific actions, and B, C, D are the correct combination. Option E is wrong because DAX is a caching layer for reads, not writes, and does not resolve write throttling.

Answer

Switch the table to on-demand capacity mode.

Answer

Enable DynamoDB Accelerator (DAX) to cache writes.

Question 13

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). AWS Database Migration Service (DMS) can migrate the Oracle database to RDS, while the AWS Schema Conversion Tool (SCT) assesses the source database and converts the schema to target format. Option A (AWS Migration Hub) tracks migrations but does not assess databases. Option B (CloudEndure Disaster Recovery) is for server-level disaster recovery, not database assessment. Option C (AWS Snowball) is for offline data transfer, not assessment or migration planning.

Answer

AWS Migration Hub

Answer

CloudEndure Disaster Recovery

Answer

AWS Snowball

Question 14

Refer to the exhibit. A DBA is checking the backup configuration of an RDS MySQL instance. The current time is 2023-03-15T06:00:00Z. What is the most recent point to which the database can be restored?

Accepted Answer

2023-03-15T04:30:00Z. The latest restorable time is 2023-03-15T04:30:00Z, which is within the backup window. Option A is incorrect because 2023-03-15T03:00:00Z is earlier than the latest restorable time, so it is not the most recent point. Option B is incorrect because 2023-03-15T05:30:00Z is later than the latest restorable time, so it is not within the backup window. Option D is incorrect because although the backup window ends at 06:00, the latest restorable time is 04:30, not 06:00.

Answer

2023-03-15T03:00:00Z

Answer

2023-03-15T05:30:00Z

Answer

2023-03-15T06:00:00Z

Question 15

Refer to the exhibit. A DBA deploys this CloudFormation stack. After creation, the DBA needs to enable deletion protection for the DB instance. Which modification to the template would accomplish this?

Accepted Answer

Add 'DeletionProtection': true to the Properties.. Adding 'DeletionProtection': true to the Properties of the AWS::RDS::DBInstance resource enables deletion protection for that DB instance. Option B is incorrect because 'DeletionPolicy: Retain' is a CloudFormation resource-level attribute that retains the resource when the stack is deleted, but it does not prevent deletion of the resource outside of CloudFormation. Option C is incorrect because 'PreventRDSDeletion' is not a valid property for RDS. Option D is incorrect because the correct syntax is 'DeletionProtection': true, not 'Enabled'.

Answer

Add 'DeletionPolicy: Retain' to the resource.

Answer

Add 'PreventRDSDeletion: true' to the Properties.

Answer

Add 'DeletionProtection': 'Enabled' to the Properties.