SOA-C03 practice question 6 of 10

A global gaming company is preparing to launch a new game on AWS. The game runs in multiple AWS Regions on a fleet of Amazon EC2 instances. The…

Domain Reliability and Business Continuity

A global gaming company is preparing to launch a new game on AWS. The game runs in multiple AWS Regions on a fleet of Amazon EC2 instances. The instances are in an Auto Scaling group behind an Application Load Balancer (ALB) in each Region. The company plans to use Amazon Route 53 for DNS services. The DNS configuration must direct users to the Region that is closest to them and must provide automated failover. Which combination of steps should a CloudOps engineer take to configure Route 53 to meet these requirements? (Select TWO.)

Answer options

A: Create Amazon CloudWatch alarms that monitor the health of the ALB in each Region. Configure Route 53 DNS failover by using a health check that monitors the alarms. Correct answer

B: Create Amazon CloudWatch alarms that monitor the health of the EC2 instances in each Region. Configure Route 53 DNS failover by using a health check that monitors the alarms.

C: Configure Route 53 DNS failover by using a health check that monitors the private IP address of an EC2 instance in each Region.

D: Configure Route 53 geoproximity routing. Specify the Regions that are used for the infrastructure. Correct answer

E: Configure Route 53 simple routing. Specify the continent, country, and state or province that are used for the infrastructure.

Correct Answer:

A. Create Amazon CloudWatch alarms that monitor the health of the ALB in each Region. Configure Route 53 DNS failover by using a health check that monitors the alarms.; D. Configure Route 53 geoproximity routing. Specify the Regions that are used for the infrastructure.

Explanation

To meet the requirement of directing users to the closest AWS Region, Amazon Route 53 geoproximity routing is the appropriate policy. This policy routes traffic based on the geographic location of both the users and the configured AWS resources, effectively sending users to the nearest endpoint. For automated failover, Route 53 must be able to determine the health of each regional endpoint. The most reliable method in this architecture is to monitor the Application Load Balancer (ALB) in each region. A CloudWatch alarm can be configured to trigger if the ALB becomes unhealthy (e.g., the HealthyHostCount metric drops below a threshold). A Route 53 health check can then monitor the state of this CloudWatch alarm, allowing Route 53 to automatically stop sending traffic to an unhealthy region.

Why Incorrect

B. Monitoring individual EC2 instances is less effective than monitoring the ALB, which provides an aggregated health status for the entire fleet of instances in that region.
C. Route 53 health checkers operate from the public internet and cannot reach private IP addresses of EC2 instances. Also, a single instance's health doesn't represent the region's availability.
E. Simple routing does not support routing based on user location. The description of specifying continent and country applies to geolocation routing, not simple routing, making the option incorrect.

References

1. Amazon Route 53 Developer Guide - Geoproximity routing: "Geoproximity routing lets Amazon Route 53 route traffic to your resources based on the geographic location of your users and your resources." This directly supports using geoproximity to route users to the closest region.

Source: AWS Documentation

Amazon Route 53 Developer Guide

"Choosing a routing policy

" section "Geoproximity routing."

2. Amazon Route 53 Developer Guide - Health checks that monitor a CloudWatch alarm: "You can create a health check that monitors a CloudWatch alarm... For example

you can create a CloudWatch alarm that monitors the status of an Application Load Balancer..." This confirms that monitoring an ALB's health via a CloudWatch alarm is a supported and recommended pattern for Route 53 health checks.

Source: AWS Documentation

Amazon Route 53 Developer Guide

"How Amazon Route 53 determines whether a health check is healthy

" section "Health checks that monitor a CloudWatch alarm."

3. Amazon Route 53 Developer Guide - Configuring DNS failover: "Route 53 health checks monitor the health of your resources... When a resource becomes unavailable

Route 53 can detect that and stop including the corresponding resource record when responding to DNS queries." This explains the mechanism for automated failover.

Source: AWS Documentation

Amazon Route 53 Developer Guide

"Concepts

" section "Health checks and DNS failover."

4. Elastic Load Balancing User Guide - Health checks for your Target Groups: "The load balancer periodically sends requests to its registered targets to test their status... The load balancer routes requests only to the healthy targets." The ALB's health status is an aggregate of its targets

making it the ideal metric for regional health.

Source: AWS Documentation

Elastic Load Balancing User Guide for Application Load Balancers

"Target Groups for Your Application Load Balancers

" section "Health checks for your target groups."

Question breakdown

Tests: Configure Route 53 routing policies and health-check-based failover
Difficulty: Medium

Key idea: Geoproximity routing sends users to the nearest Region, and a health check tied to a CloudWatch alarm on each ALB removes an unhealthy Region from DNS answers.

How to reach the answer

Two needs are stated: route to the closest Region, and fail over automatically.
For 'closest Region', geoproximity routes on user and resource location. Simple routing has no location awareness.
For failover, the ALB is the regional entry point and reflects the health of the whole fleet behind it.
A CloudWatch alarm on an ALB metric such as HealthyHostCount can drive a Route 53 health check.
Private IP checks cannot work because Route 53 health checkers run from the internet.

Each option

ACorrect. A Route 53 health check that tracks a CloudWatch alarm on each Region's ALB gives Route 53 a Region-level signal for automated failover.
BIncorrect. Alarms on individual instances in a scaling fleet do not represent the Region's overall availability the way the ALB does.
CIncorrect. Route 53 health checkers cannot reach private IP addresses, and one instance does not represent the Region's health.
DCorrect. Geoproximity routing directs each user to the Region whose resources are geographically closest.
EIncorrect. Simple routing has no location-based logic; continent, country and state settings belong to geolocation routing.

Common trap: Option B looks equivalent to A, but in an Auto Scaling fleet the ALB is the correct aggregated health signal, not individual instances.

In practice: Multi-Region active-active applications commonly pair a location-aware routing policy with health checks on the regional load balancer. This lets DNS steer users away from a failed Region.

Remember: Health-check the regional entry point (the ALB), not individual or private instances, and pick a routing policy that matches the 'closest' requirement.

Official documentation: Geoproximity routing · Configuring DNS failover

Reviewed by David Mercer.

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