SAA-C03 practice question 6 of 35

A company serves its website by using an Auto Scaling group of Amazon EC2 instances in a single AWS Region. The website does not require a database…

Choose your answer, then check it against the explanation and the full breakdown below.

Domain Design Resilient Architectures

A company serves its website by using an Auto Scaling group of Amazon EC2 instances in a single AWS Region. The website does not require a database The company is expanding, and the company's engineering team deploys the website to a second Region. The company wants to distribute traffic across both Regions to accommodate growth and for disaster recovery purposes The solution should not serve traffic from a Region in which the website is unhealthy. Which policy or resource should the company use to meet these requirements?

Answer options

Correct Answer:

Explanation

Amazon Route 53 is the appropriate service for directing traffic to multiple AWS Regions. The multivalue answer routing policy allows Route 53 to respond to DNS queries with up to eight healthy records selected at random. By creating a record for the endpoint in each Region (e.g., the regional Application Load Balancer) and associating a Route 53 health check with each record, the requirements are met. This configuration distributes traffic across both Regions. If the health check for one Region fails, Route 53 will stop returning that Region's record in DNS responses, effectively routing traffic away from the unhealthy endpoint and providing disaster recovery.

Why Incorrect

A. A simple routing policy routes traffic to a single resource. While you can specify multiple values, it does not perform health checks to remove unhealthy endpoints from responses.

C. An Application Load Balancer is a regional service. Its target groups cannot contain EC2 instances that reside in a different AWS Region.

D. An Application Load Balancer is regional and cannot have targets in another Region. This design also introduces a single point of failure in the primary Region.

References

1. Amazon Route 53 Developer Guide: In the section "Choosing a routing policy

" it states

"Multivalue answer routing: Use when you want Route 53 to respond to DNS queries with up to eight healthy records selected at random." It further clarifies

"If you associate a health check with a multivalue answer record

Route 53 responds to DNS queries with only the records that are healthy." (See section: "Choosing a routing policy

" subsection: "Multivalue answer routing").

2. AWS Documentation - What is Elastic Load Balancing?: This document describes the scope of load balancers. "Elastic Load Balancing distributes incoming application traffic across multiple targets

such as Amazon EC2 instances... in a single Availability Zone or across multiple Availability Zones." This confirms the regional nature of the service. (See section: "Elastic Load Balancing components

" paragraph on "Load balancer").

3. Elastic Load Balancing User Guide: When registering targets

the documentation specifies they must be within the load balancer's VPC. "You can register targets by instance ID or by IP address. Your target group can include targets from different Availability Zones

but they must be in the same VPC as the load balancer." This explicitly prohibits registering instances from another Region. (See section: "Target groups for your Application Load Balancers

" subsection: "Register targets").

Question 6 of 35

Question breakdown

Tests: Design multi-Region DNS routing with health-based failover
Difficulty: Easy

Key idea: Route 53 multivalue answer routing returns multiple records and, when each has a health check, returns only the healthy ones.

How to reach the answer

Traffic must span two Regions, so a Regional ALB cannot be the entry point; DNS-level routing is needed.
The clue 'should not serve traffic from a Region in which the website is unhealthy' means the routing policy must support health checks.
Simple routing cannot attach health checks, so an unhealthy Region could still be returned.
Multivalue answer routing with a health check per Regional endpoint spreads traffic across both Regions and drops any unhealthy one.

Each option

AIncorrect. Simple routing can return multiple values but cannot evaluate health checks, so it would keep returning an unhealthy Region.
BCorrect. Multivalue answer records with health checks distribute DNS responses across both Regions and return only healthy endpoints.
CIncorrect. An ALB is Regional and cannot register instance IDs from another Region; it also leaves one Region as a single point of failure.
DIncorrect. ALB IP targets must be reachable private IPs tied to the load balancer's VPC context, and a single-Region ALB still fails if that Region goes down.

Common trap: Simple routing accepts multiple IP values, so it looks like it distributes traffic, but it has no health-check awareness.

In practice: Multi-Region web tiers commonly put a Regional ALB in each Region and front them with Route 53 records (multivalue, latency, weighted, or failover) backed by health checks.

Remember: For cross-Region distribution that must skip unhealthy endpoints, use a Route 53 policy that supports health checks, never simple routing.

Official documentation: Choosing a routing policy · Multivalue answer routing

Drafted with AI assistance and checked against the answer key.

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