DOP-C02 Incident and Event Response Practice Test 16 — 15 Questions

Question 1

A company uses EC2 instances in an Auto Scaling group behind an ALB. The DevOps team receives alerts that the CPU utilization on the instances is consistently above 90% during peak hours. The Auto Scaling group is configured with a simple scaling policy that adds one instance when CPU exceeds 80% and removes one when below 30%. However, during sudden traffic spikes, the scaling policy reacts too slowly, causing performance degradation. The team wants to improve the scaling responsiveness without over-provisioning. What should the team do?

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

Accepted Answer

Replace the simple scaling policy with a target tracking scaling policy based on average CPU utilization with a target value of 70%.. A target tracking scaling policy automatically adjusts the size of the Auto Scaling group to keep the average CPU utilization close to the target value (70%). This provides a proactive and responsive scaling mechanism for sudden traffic spikes without manual intervention. Option A is incorrect because increasing the cooldown period would delay scaling actions, worsening the response time. Option B is incorrect because although a step scaling policy can add multiple instances at once, it requires manual configuration of thresholds and step adjustments, and it may not adapt as smoothly to varying spikes as target tracking. Option C is incorrect because scheduled scaling only addresses predictable traffic patterns, not sudden, unpredictable spikes.

Answer

Increase the cooldown period for the simple scaling policy to allow more time for metrics to stabilize.

Answer

Replace the simple scaling policy with a step scaling policy that adds multiple instances when CPU exceeds 80%.

Answer

Create a scheduled scaling action to add instances before peak hours based on historical data.

Question 2

A company's DevOps team uses AWS Config to monitor resource compliance. They have created a custom AWS Config rule that triggers an AWS Lambda function to evaluate whether EC2 instances have the 'Environment' tag with value 'Production' or 'Staging'. The rule is set to evaluate resources on configuration changes. However, the team notices that the rule does not trigger when an EC2 instance is launched. The Lambda function's IAM role has the necessary permissions to describe EC2 instances. The CloudWatch Logs for the Lambda function show that it is not being invoked. What is the MOST likely reason?

Accepted Answer

The AWS Config rule is not configured to trigger on AWS::EC2::Instance resources.. The AWS Config rule is not configured to trigger on AWS::EC2::Instance resources. For a custom AWS Config rule to evaluate a specific resource type, the rule must have its scope set to that resource type. The rule likely only evaluates a different resource type (e.g., AWS::EC2::SecurityGroup) or has no scope defined, so it does not trigger on EC2 instance launches. Option A is incorrect because the Lambda function is not being invoked at all; CloudWatch Logs permissions are irrelevant if the function is not triggered. Option B is incorrect because the rule is set to evaluate on configuration changes, not periodically. Option D is incorrect because custom rules can be created via the AWS Config console or API; CloudFormation is not required.

Answer

The Lambda function's IAM role does not have permission to write to CloudWatch Logs.

Answer

The AWS Config rule is set to evaluate resources periodically, not on configuration changes.

Answer

The custom rule must be deployed using AWS CloudFormation to be active.

Question 3

A company uses Amazon RDS for MySQL with Multi-AZ deployment. The database instance fails and AWS automatically fails over to the standby. After the failover, the application cannot connect to the database. The engineer checks the RDS console and sees that the instance status is Available. What is the MOST likely cause of the connectivity issue?

Accepted Answer

The application is using the database's DNS endpoint for the old primary, which is no longer the writer.. After an RDS Multi-AZ failover, the DNS endpoint for the DB instance remains the same but its underlying IP address changes to point to the new primary (formerly the standby). If the application caches the IP address of the old primary or uses a direct connection to the old writer endpoint, it will attempt to connect to a node that is no longer the writer. The correct practice is to always connect using the RDS instance endpoint (CNAME), which automatically resolves to the current writer, and to avoid caching the resolved IP address. Since the instance status is 'Available', the new primary is ready, so the issue is a stale connection target.

Answer

The security group for the RDS instance has changed during failover.

Answer

The DNS record for the RDS endpoint has not propagated to the application's DNS resolver.

Answer

The database instance is still in the process of failover and is not yet accepting connections.

Question 4

An IAM policy is attached to a role used by an operations team. The team reports that they are unable to start or stop EC2 instances tagged with Environment=Production. Other instances can be described. What is the MOST likely reason for this failure?

Accepted Answer

The condition key ec2:ResourceTag/Environment is not valid for ec2:StartInstances and ec2:StopInstances.. The `ec2:ResourceTag` condition key is not supported for the `ec2:StartInstances` and `ec2:StopInstances` actions in IAM policy evaluation. AWS documentation explicitly states that these actions do not support resource-level permissions based on tags; they only support the `ec2:ResourceTag` condition key for certain read-only or tagging actions. Therefore, the condition in the policy cannot be evaluated, causing the operations team to fail when attempting to start or stop Production-tagged instances.

Answer

The role does not have permission to describe instances, so the condition cannot be evaluated.

Answer

The policy's Resource element is set to '*' and must be restricted to specific instance ARNs.

Answer

The policy does not include the ec2:RebootInstances action.

Question 5

A company uses AWS Organizations with multiple accounts. The security team needs to automatically isolate a compromised EC2 instance by removing it from its security group and attaching a quarantine security group that only allows traffic to a forensic instance. Which combination of actions should be implemented?

Accepted Answer

Use AWS Config rules with AWS Systems Manager Automation documents to automatically remove the instance from the security group and attach the quarantine group when non-compliant.. AWS Config rules can evaluate security group membership compliance, and when a non-compliant EC2 instance is detected, an AWS Systems Manager Automation document can be triggered via a remediation action. This automation document can execute the steps to remove the instance from its current security group and attach a quarantine security group, providing a fully automated, event-driven isolation workflow without requiring custom code for orchestration.

Answer

Use Amazon GuardDuty to automatically modify the security group membership of the instance.

Answer

Use AWS Shield Advanced to automatically apply the quarantine security group to the instance.

Answer

Use AWS Lambda functions triggered by Amazon EventBridge to remove the instance from the security group and attach the quarantine group.

Question 6

A DevOps engineer notices that an EC2 instance in an Auto Scaling group is repeatedly failing health checks and being terminated. The engineer needs to capture the root cause by collecting memory dumps and system logs before termination. What should the engineer do?

Accepted Answer

Use EC2Rescue for Windows Server or Linux, configure it to run at instance startup, and extend the Auto Scaling health check grace period.. EC2Rescue is specifically designed to collect memory dumps and system logs from EC2 instances, and by configuring it to run at startup and extending the Auto Scaling health check grace period, the engineer ensures diagnostics are captured before the instance is terminated for failing health checks. This approach directly addresses the need to gather root cause data from a failing instance that is about to be replaced.

Answer

Configure the CloudWatch Agent to collect memory and system logs and publish them to CloudWatch Logs.

Answer

Use AWS Systems Manager Run Command to execute a script on the instance that collects diagnostics before it is terminated.

Answer

Enable EC2 instance metadata service (IMDS) to capture diagnostic data that persists after termination.

Question 7

A company is using AWS CloudFormation to deploy infrastructure. An engineer needs to ensure that any changes to the production stack are reviewed and approved before they are applied. The engineer also wants to prevent unauthorized changes. Which solution should the engineer implement?

Accepted Answer

Use CloudFormation Change Sets and require manual approval to execute the change set.. CloudFormation Change Sets allow you to preview how proposed changes to a stack will impact running resources before you apply them. By requiring manual approval to execute the change set, the engineer ensures that all modifications are reviewed and approved, preventing unauthorized changes. This directly meets the requirement for a review-and-approval workflow without introducing unnecessary complexity.

Answer

Use CloudFormation StackSets to manage the production stack across multiple accounts.

Answer

Use AWS Service Catalog to create a product for the stack and require approval for any portfolio changes.

Answer

Use AWS CodePipeline to deploy the stack and require manual approval at the deploy stage.

Question 8

A company runs a critical web application on AWS. The application is deployed across multiple Availability Zones using an Application Load Balancer (ALB) with an Auto Scaling group of EC2 instances. The Auto Scaling group uses a launch template that specifies an Amazon Linux 2 AMI. The application stores session state in an ElastiCache Redis cluster. Recently, the operations team received alerts that the application is returning 503 errors intermittently. Investigation shows that the ALB target group health checks are failing for some instances, but those instances are still in service. The CloudWatch logs from the instances show that the application is running, but the health check endpoint is timing out after 5 seconds. The health check is configured with a 5-second timeout, 10-second interval, and 2 consecutive successes required to mark healthy. The DevOps engineer suspects that the issue is due to high CPU utilization on the instances causing the health check to respond slowly. The engineer wants to implement a solution that prevents the ALB from routing traffic to instances that are experiencing high CPU, and also automatically scales out to handle the increased load. What should the engineer do?

Accepted Answer

Create a CloudWatch alarm on CPU utilization and use it to perform an EC2 action to stop the instance, and configure the Auto Scaling group to use a target tracking scaling policy based on CPU utilization.. It addresses both the immediate issue (high CPU causing health check timeouts) and the scaling requirement. Stopping the instance via a CloudWatch alarm removes it from the ALB target group, preventing traffic routing to unhealthy instances. The target tracking scaling policy based on CPU utilization automatically adds instances when CPU is high, ensuring capacity matches demand.

Answer

Configure the Auto Scaling group to use ELB health checks and set the health check grace period to 600 seconds.

Answer

Create a scheduled scaling action to add more instances during peak hours.

Answer

Increase the health check timeout to 10 seconds and the interval to 20 seconds to give instances more time to respond.

Question 9

A company uses AWS CloudTrail to audit API activity. During an incident investigation, they find that a user with the IAM policy 'AdministratorAccess' deleted an S3 bucket. The security team wants to know the source IP address and user agent used for the delete operation. Which action should the team take to obtain this information?

Accepted Answer

View the CloudTrail event history for the delete-bucket event.. CloudTrail event history captures all management events, including DeleteBucket, and records the source IP address and user agent for each API call. By viewing the event history for the specific delete-bucket event, the security team can directly retrieve the required metadata without needing additional log sources or configurations. Option B is incorrect because S3 server access logs log object-level operations, not management events like bucket deletion. Option C is not the most direct method; CloudWatch Logs can be used if CloudTrail is configured to send events to a log group, but the simplest way is from CloudTrail event history directly. Option D is incorrect because AWS Config tracks resource configuration changes, not API call details like source IP.

Answer

Check the S3 server access logs for the deleted bucket.

Answer

Use CloudWatch Logs to search for the event in the CloudTrail log group.

Answer

Query AWS Config to find the configuration item for the bucket deletion.

Question 10

A company uses AWS Organizations with multiple accounts. The security team wants to ensure that all IAM roles in member accounts have a maximum session duration of 1 hour. They need a way to detect any roles that violate this policy. What should they do?

Accepted Answer

Use AWS Config with the managed rule iam-role-max-session-duration to evaluate roles.. AWS Config provides a managed rule called `iam-role-max-session-duration` that specifically evaluates IAM roles to ensure their `MaxSessionDuration` setting does not exceed a specified threshold (default 1 hour). This rule can be deployed across all member accounts in AWS Organizations using a conformance pack or AWS Config aggregator, allowing the security team to continuously detect and report any roles that violate the policy without manual intervention.

Answer

Use IAM Access Analyzer to validate the roles against a policy template.

Answer

Run AWS Trusted Advisor and check the IAM report for roles with long session durations.

Answer

Enable AWS CloudTrail and create a metric filter to detect role creation with session duration greater than 1 hour.

Question 11

A DevOps engineer is troubleshooting an application running on an EC2 instance. The application needs to access an Amazon RDS database using IAM database authentication. The EC2 instance is associated with an IAM role 'EC2-AppRole', and the RDS instance has a resource-based policy that allows 'DatabaseAccessRole' to connect. The engineer sees the error in the exhibit. What is the most likely cause?

Accepted Answer

The trust policy of the IAM role 'DatabaseAccessRole' does not allow the EC2 instance role 'EC2-AppRole' to assume it.. The error indicates that the EC2 instance's IAM role 'EC2-AppRole' cannot authenticate to the RDS instance. IAM database authentication requires the EC2 instance to assume a database authentication token, which is generated by calling the RDS API with the 'EC2-AppRole' credentials. However, the RDS instance's resource-based policy only allows 'DatabaseAccessRole' to connect. For 'EC2-AppRole' to successfully authenticate, it must first assume 'DatabaseAccessRole' via a trust policy that permits the EC2 instance role to assume it. Without this trust relationship, the authentication token request fails, causing the error.

Answer

The RDS instance does not have a resource-based policy that grants access to 'DatabaseAccessRole'.

Answer

The security group for the EC2 instance does not allow outbound traffic to the RDS instance.

Answer

The EC2 instance does not have the correct IAM instance profile attached.

Question 12

A company runs a multi-tier web application on AWS. The application consists of an Application Load Balancer (ALB), an EC2 Auto Scaling group (ASG) for web servers, and an Amazon RDS Multi-AZ DB instance. The ASG uses a launch template with Amazon Linux 2 and a user data script that installs the web application and connects to the RDS database using a static password stored in the user data. Recently, the security team discovered that the user data script is exposed in the EC2 console and could be viewed by anyone with EC2 describe-instances permissions. The team wants to remediate this immediately without causing downtime. The ASG is configured with a min size of 2, max size of 6, and desired capacity of 4. The application is currently under load. Which option describes the best course of action?

Accepted Answer

Create a new launch template version that retrieves the password from AWS Secrets Manager. Update the ASG to use the new template version and perform an instance refresh with a minimum healthy percentage of 100%.. It uses an instance refresh with a minimum healthy percentage of 100% to replace instances without downtime, while the new launch template version retrieves the password from AWS Secrets Manager, eliminating the static password exposure. This approach ensures that the security vulnerability is remediated immediately without disrupting the running application under load.

Answer

Immediately modify the user data on each running EC2 instance to remove the password, then update the launch template to reference AWS Secrets Manager.

Answer

Update the existing launch template to use AWS Secrets Manager for the database password. The ASG will automatically apply the change to existing instances.

Answer

Delete the existing launch template and create a new one with secrets from AWS Secrets Manager. Then terminate all running instances and let the ASG launch new ones.

Question 13

An incident response team is analyzing an IAM policy attached to a role used by a forensic tool. The tool needs to create snapshots of EBS volumes during an incident. However, when the tool runs from an IP address in the 203.0.113.0/24 range, the CreateSnapshot API call fails with an access denied error. What is the MOST likely cause?

Accepted Answer

The aws:ViaAWSService condition is set to false, but the tool is invoked by an AWS service such as Systems Manager, making the condition evaluate to true and denying access.. The aws:ViaAWSService condition key evaluates to true when an API call is made by an AWS service on behalf of a principal. If the policy sets this condition to false, it denies any call that originates from an AWS service (e.g., Systems Manager Automation). In this scenario, the forensic tool is likely invoked by Systems Manager, causing the condition to evaluate to true and triggering the deny, even though the source IP is allowed. This explains why CreateSnapshot fails with access denied despite the IP being in the allowed range.

Answer

The policy does not grant ec2:CreateSnapshot on specific resource ARNs, only on all resources.

Answer

The Deny statement explicitly denies ec2:DeleteSnapshot, but the error is for CreateSnapshot, so it is unrelated.

Answer

The source IP address 203.0.113.0/24 is not included in the Condition block, so access is implicitly denied.

Question 14

A company uses Amazon CloudWatch Synthetics canaries to monitor its web application endpoints. The canaries are failing intermittently with 'ClientError' status codes. Which TWO actions should the engineer take to diagnose the issue? (Choose two.)

Accepted Answer

Review the canary's CloudWatch Logs for error details.. CloudWatch Synthetics canaries automatically log execution details, including errors, to CloudWatch Logs. Reviewing these logs provides specific error information, such as 'ClientError' details. Option C is correct because each canary runs as an AWS Lambda function, and the Lambda function's CloudWatch Logs contain runtime logs, including any exceptions or errors thrown during execution. Option A is incorrect because while adding logging could be a long-term improvement, the question asks for diagnostic actions; the canary already logs to CloudWatch Logs, so modifying the script is not necessary for diagnosis. Option D is incorrect because CloudWatch metrics provide aggregate statistics (e.g., success/failure rates) but not detailed error codes or messages. Option E is incorrect because CloudTrail records API calls to create, start, or stop canaries, not the execution details of individual canary runs.

Answer

Modify the canary script to add more logging.

Answer

Examine CloudWatch metrics for the canary.

Answer

Check CloudTrail for CanaryRun API calls.

Question 15

Refer to the exhibit. An IAM policy is attached to a user. The user tries to upload an object to the S3 bucket 'my-bucket' without server-side encryption. What will happen?

Accepted Answer

The upload fails with an Access Denied error.. The upload fails with an Access Denied error because the IAM policy attached to the user includes a condition that requires the request to include the `x-amz-server-side-encryption` header with a value of `AES256`. Since the user attempts to upload without specifying any server-side encryption, the request does not satisfy the condition and is denied. Option A is incorrect because the policy denies unencrypted uploads. Option B is incorrect because the user did not request SSE-S3. Option C is incorrect because automatic encryption does not override the IAM policy condition; the policy explicitly requires the encryption header to be present in the request.

Answer

The upload succeeds without encryption.

Answer

The upload succeeds with SSE-S3 encryption.

Answer

The upload succeeds and is automatically encrypted with SSE-S3.