A team wants a web application to keep serving traffic if one Availability Zone fails. Match each architecture element to the resilience behavior it provides.
Drag a concept onto its matching description — or click a concept then click the description.
Stop sending requests to unhealthy targets and keep only healthy instances in rotation.
Launch replacement instances in healthy AZs when capacity is lost.
Maintain a synchronous standby in another AZ and fail over automatically.
Allow instances to be replaced without losing user sessions that are stored elsewhere.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Elastic Load Balancer: Distributes incoming traffic across multiple targets in multiple Availability Zones
These pairs match architecture elements with their resilience behaviors for surviving an Availability Zone failure, focusing on AWS services that provide high availability and fault tolerance.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Elastic Load Balancer: Distributes incoming traffic across multiple targets in multiple Availability Zones
Why this is correct
An Elastic Load Balancer (ELB) is crucial for high availability by distributing incoming application traffic across multiple EC2 instances, containers, or IP addresses. It operates across multiple Availability Zones (AZs) within a region, automatically routing requests only to healthy targets. If an instance or an entire AZ becomes unhealthy, the ELB stops sending traffic to it, ensuring the web application remains accessible to users.
Auto Scaling Group: Automatically replaces unhealthy instances and maintains desired capacity across Availability Zones
Why this is correct
An Auto Scaling Group (ASG) enhances web application resilience by automatically replacing unhealthy EC2 instances, detected via health checks, and launching new ones. It ensures that the desired number of instances is maintained across specified Availability Zones. If an AZ experiences an outage, the ASG can launch new instances in healthy AZs to compensate, thereby maintaining application capacity and availability.
Amazon RDS Multi-AZ: Provides automatic failover to a standby database instance in a different Availability Zone
Why this is correct
Amazon RDS Multi-AZ deployments provide high availability and durability for relational databases by synchronously replicating data to a standby instance in a different Availability Zone. In the event of an infrastructure failure, such as an AZ outage or primary database instance failure, RDS automatically fails over to the standby. This process ensures minimal downtime and continuous database operations for the web application.
Amazon Route 53: Routes end users to healthy endpoints using DNS health checks and failover
Why this is correct
Amazon Route 53, as a highly available and scalable cloud DNS web service, contributes to application resilience by routing end-user requests to healthy endpoints. It uses DNS health checks to monitor the health of resources, such as ELBs or EC2 instances, across different Availability Zones. If an endpoint becomes unhealthy, Route 53 can automatically reroute traffic to a healthy alternative using failover routing policies, ensuring continuous service.
Amazon S3: Automatically fails over to a secondary region in case of an Availability Zone failure
Why it's wrong here
Amazon S3 is an object storage service designed for 99.999999999% (11 nines) durability and high availability by storing data redundantly across multiple devices in a minimum of three Availability Zones within a single AWS Region. Therefore, an individual Availability Zone failure does not impact S3's availability or durability. S3 does not automatically fail over to a secondary region in response to an AZ failure; cross-region replication is a separate configuration for disaster recovery, not automatic AZ failover.
AWS CloudFormation: Distributes application load across multiple Availability Zones
Why it's wrong here
AWS CloudFormation is an Infrastructure as Code (IaC) service that allows users to define and provision AWS infrastructure resources in a declarative way using templates. Its primary function is to automate the deployment and management of resources, such as EC2 instances, databases, and networks. CloudFormation itself does not actively distribute application load or manage traffic across Availability Zones; it merely provisions the resources that perform these functions.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAA-C03 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAA-C03 exam.