SOA-C02 Reliability and Business Continuity Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Use a single large EC2 instance instead of multiple instances

  Why it's wrong here

  Using a single large EC2 instance instead of multiple smaller ones creates a single point of failure; if the instance fails or the underlying hardware experiences issues, the application becomes completely unavailable. It also prevents the use of an Application Load Balancer to distribute traffic across multiple healthy targets, and scaling requires downtime to modify the instance type. This approach provides no redundancy and does not align with high-availability design principles.

• ✗

  Disable health checks on the ALB to avoid false positives

  Why it's wrong here

  Disabling health checks on the ALB is dangerous because the load balancer relies on health checks to determine which EC2 instances are capable of receiving traffic. Without them, the ALB would continue sending requests to failed or degraded instances, resulting in 5xx errors for users. Additionally, Auto Scaling uses the ELB health check to automatically replace unhealthy instances, so disabling it would prevent the group from maintaining desired capacity and would mask underlying issues.

• ✓

  Configure the Auto Scaling group to launch instances in at least two Availability Zones

  Why this is correct

  Configuring the Auto Scaling group to launch instances in at least two Availability Zones is the correct approach for high availability because it isolates the application from a single-AZ failure. If one AZ becomes unavailable, the ASG automatically launches new instances in another AZ and the ALB routes traffic only to healthy instances in the remaining AZs. This distribution also supports even scaling and aligns with the AWS Well-Architected Framework's reliability pillar.

• ✗

  Launch all EC2 instances in a single Availability Zone

  Why it's wrong here

  Launching all EC2 instances in a single Availability Zone leaves the application vulnerable to a complete outage if that specific AZ experiences a disruption such as a power failure or network issue. Even if multiple instances are running, they all share the same physical infrastructure and network dependencies, so there is no failure isolation. This design violates the high-availability requirement because the entire application depends on the availability of one AZ.

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