How should CloudWatch Synthetics monitor customer routes with 95% availability?

Implement metrics, alarms, and filters by using AWS monitoring and logging services. Identify and remediate issues by using monitoring and availability metrics.

Answer Correct answer: A — Use a CloudWatch Synthetics canary that follows customer routes and alarm when its SuccessPercent metric falls below 95%, publishing to SNS.

A company hosts a web application on Amazon EC2 instances behind an Application Load Balancer. The instances are in an Amazon EC2 Auto Scaling group. The application is accessed with a public URL. A CloudOps engineer needs to implement a monitoring solution that checks the availability of the application and follows the same routes and actions as a customer. The CloudOps engineer must receive a notification if less than 95% of the monitoring runs find no errors. Which solution will meet these requirements?

Create an Amazon CloudWatch Synthetics canary with a script that follows customer routes. Schedule the canary to run on a recurring schedule. Create a CloudWatch alarm that publishes a message to an Amazon SNS topic when the SuccessPercent metric is less than 95%. Correct Answer
Create Amazon Route 53 health checks that monitor the availability of the endpoint. Create Amazon CloudWatch alarms that publish a message to an Amazon SNS topic when the HealthCheckPercentageHealthy metric is less than 95%.
Create a single AWS Lambda function to check whether the endpoints are available for each customer path. Schedule the Lambda function by using Amazon EventBridge. Configure the Lambda function to publish a message to an Amazon SNS topic when an endpoint returns an error.
Create an AWS Lambda function for each customer path to check whether that specific endpoint is available. Schedule the Lambda functions by using Amazon EventBridge. Configure each Lambda function to publish a custom metric to Amazon CloudWatch for the endpoint status. Create CloudWatch alarms based on each custom metric to publish a message to an Amazon SNS topic when an alarm is in the ALARM state.

Community Insight

It tests selection of synthetic user-journey monitoring plus a percentage-of-runs alarm; the trap is Route 53 health checks, which only test endpoint availability and cannot replay customer routes.

This question asks for application availability monitoring that replays customer routes and alerts when fewer than 95% of runs are error-free. The correct design is a CloudWatch Synthetics canary whose SuccessPercent metric drives an SNS-backed CloudWatch alarm.

Choosing Route 53 health checks because they sound like availability monitoring, even though they cannot follow customer routes or actions and HealthCheckPercentageHealthy is not the scripted-run SuccessPercent metric.

Community Discussion (1 comments)

Bad_Mat 👍 1 Selected: A

A. Create an Amazon CloudWatch Synthetics canary with a script that follows customer routes. Schedule the canary to run on a recurring schedule. Create a CloudWatch alarm that publishes a message to an Amazon SNS topic when the SuccessPercent metric is less than 95%.

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Expert Analysis

Why the Answer Is Correct

A CloudWatch Synthetics canary runs a scripted browser or HTTP workflow on a recurring schedule, so it can traverse the same routes and actions as a customer instead of only pinging a single endpoint. The canary emits SuccessPercent, which represents the percentage of runs that completed without failing steps, so an alarm below 95% directly matches the notification condition. SNS integration then delivers the alert to the CloudOps engineer. This satisfies both route fidelity and the percentage-of-runs threshold in one managed solution.

Why the Other Options Are Wrong

Route 53 health checks can monitor endpoint health and integrate with CloudWatch, but they cannot replay customer routes or multi-step actions, and HealthCheckPercentageHealthy is not a drop-in measure of scripted run success. A single Lambda function could script checks, but you would build scheduling, error aggregation, metric publication, and alarming yourself, and a single function does not naturally produce a percentage-of-runs success metric. Per-path Lambda functions add more custom metrics and alarms, but they still do not provide the managed canary workflow nor a simple SuccessPercent threshold across all customer paths.

Community Comment Notes

Bad_Mat endorsed option A, pointing specifically at the CloudWatch Synthetics canary that follows customer routes and alarms on SuccessPercent below 95%. That matches the wording of the requirement, which asks for the same routes and actions as a customer plus a notification when fewer than 95% of monitoring runs are error-free. The comment does not raise any competing interpretation of the Route 53 or Lambda options.

Official Reference

Exam Strategy

Separate synthetic workflow monitoring from simple endpoint health: if the stem says the check must follow customer routes or actions, look for a CloudWatch Synthetics canary rather than a Route 53 health check. Then verify that the alarm metric matches the stated percentage-of-runs condition, which is SuccessPercent here.

Frequently Asked Questions

Why can't Route 53 health checks follow customer routes like a Synthetics canary?

Route 53 health checks test endpoint reachability, not scripted multi-step user journeys. They cannot replay the same routes and actions that a CloudWatch Synthetics canary script performs.

Does SuccessPercent below 95% mean 95% of canary runs had errors?

No. SuccessPercent is the percentage of canary runs that succeeded; an alarm below 95% fires when more than 5% of runs fail, matching the fewer-than-95%-error-free requirement.

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