A company is migrating a critical application to AWS using a rehost (lift-and-shift) approach. The application consists of a web tier and a database tier. The company wants to ensure high availability and disaster recovery. Which TWO actions should the company take? (Choose TWO.)
Spreading the web tier across multiple Availability Zones places instances behind an Application Load Balancer, so an AZ failure does not take the application offline. This satisfies the high availability and disaster recovery requirement without altering the rehosted application's architecture or code.
Why this answer
Option B is correct because deploying the web tier across multiple Availability Zones ensures that if one AZ fails, the application remains available through instances in another AZ, which is a fundamental high-availability design for a rehosted web tier on EC2. Option C is correct because Amazon RDS Multi-AZ maintains a synchronous standby replica in a different AZ and automatically fails over the database endpoint during an AZ outage or primary failure, providing high availability for the database tier. Option A is not appropriate because EC2 Auto Scaling operates within a single Region across AZs; it cannot launch instances across multiple AWS Regions, and cross-Region scaling is not a standard Auto Scaling capability.
Option D is not the best fit because read replicas are primarily for scaling read-heavy workloads and are asynchronous, so they do not provide automatic failover for high availability. Option E is incorrect because confining the database to a single AZ creates a single point of failure and undermines the disaster recovery and high availability goals.
Exam trap
SAP-C02 often tests the confusion between Multi-AZ (synchronous HA, automatic failover) and read replicas (asynchronous, read scaling/DR) — candidates pick read replicas for HA when Multi-AZ is the correct answer.